Conceptual Gods
The Birth of Gods
Gods are curious beings, born of belief and developed through devotion. They are formed when people find something new to worship, to prize above all else. Sometimes this is conscious, sometimes unconscious, but as soon as someone finds something new to believe in, a deity appears for them to serve. It doesn't take conscious action - simply striving towards this value keeps the deity alive. However, they can be actively served, by way of rituals performed in their name, and they are also nourished by true believers - those who genuinely hold that ideal as highest in their hearts. This helps the deity to flourish, to have more active influence in the world - but that's a topic for later.
Gods can be born intentionally or by accident. Sometimes people will actively choose to worship something specific, others will hold high a certain ideal in themself - either way, a deity finds themself in existence. It doesn't really matter how, the end result is much the same. The First Believer tends to have a closer connection with the deity than most, due to it being born of their belief, although this is also while the god is still young and relatively unknown, so their power is limited. The First Believer is the deity's first introduction to existence, and also the plane the believer resides in, and they are often emotionally significant to the god, being both their beginning, and after they die, their first introduction to loss.
When a god is first born, they have very little influence over planes outside their own. Through more believers and rituals, they can grow in influence, and affect more things outside their own plane. With enough effort, a god can become very powerful, whereas others remain obscure and have subtler impacts on mortal planes. On their own plane, they may interact with other gods - some do this a lot, whereas others prefer to remain private.
Sometimes, but very rarely, enough people can focus on a specific region of the domain of a god for it to split. The original god will remain much the same as they were - an ideal is still an ideal after all - but the new god is often referred to as the child of the first. The new god will be much the same as any new god, but will often have more influence to begin with, due to enough people needing to believe in them for them to split in the first place, and also benefiting from the guidance of the original (provided the original doesn't resent their child for taking some of their domain). However, they have no single First Believer, as there simply wasn't one, so that is their main difference from other deities.
Unfortunately, new gods not formed of splits have no guidance of their own - they begin in isolation, with only a very limited ability to reach into the plane it was created from, and only once they have grown a little are they able to leave their domain in their plane to interact with others. It is important to note that deities are not perfect. Especially while they are young, they make mistakes - it is only through time that they develop knowledge and wisdom of how best to impact the world (though some seem never to learn), and eventually, over millennia, attain a timeless wisdom that few outside of deities can match.
Gods as Entities
Deities are manifestations of things mortals strive for - with a little true belief to give them a beginning, they can form, grow, and wield awe-inspiring power. They are also, in a sense, the distillation of mortality - created by them, fueled by them, and the anthropomorphism of their concepts. It seems natural, then, that deities are simultaneously divine and flawed. After all, no mortal creation is perfect. Put simply, a god is a pure concept given existence. Anything that people hold dear is a deity, such as: wealth, companionship, duty, service, rebellion, or just a job well done.
Gods are classified according to three different measures - their age, their domain root type, and their following. Their age is roughly self-explanatory. Only a few gods know their actual age, as they tend not to keep track themselves, but their followers might if they are a newer deity, and sometimes celebrate that yearly. Age is known in terms such as 'old', 'mature', 'newborn', etc. and it is a measure of expected wisdom, not power, though gods that are both powerful and old are a force to reckon with. It is also worth noting that gods cannot die. There is always the potential for someone in the future to believe in them. However, with no true believers, followers, or kinpeople, they can have no influence over any plane and are consigned to an unspecified time of utter boredom.
Following is also pretty easy to understand - roughly how many true believers, followers, and kinpeople a deity has (these terms are explained below). This determines where their strength comes from, and how much they will have. A relatively new god can wield immense power, whereas an ancient one can be forgotten. It all depends how many people worship them or perform rituals in their name, as that is where they draw their strength and power from. Some gods are known as Ritual Gods. These gods have very few true believers, but a myriad of followers - people who perform rituals in their name. They tend to be somewhat weaker than the most powerful of gods (those with many true believers and followers), but still with considerable influence. They have power, but like most deities, they tend to focus it primarily on their true believers. Equally, they cannot go against their nature, and Ritual Gods are often the most misunderstood by their followers, due to there being very few true believers to correct them. There is no use making an offering to a god of the power of nature in the hopes of being avoided - they are fundamentally natural, fundamentally wild, fundamentally inhuman. THey will not spare those who perform rituals for them, nor their true believers. They cannot - they are tied to the inevitability and spontanaeity of natural events, and cannot distinguish themself from that. However, they may give some of their power to a true believer, allowing that mortal to harness that power for whatever they see fit, including, perhaps, protection from the storm.
The more complex and nebulous measure is domain type. There are three broad categories - pure concept, emulated concept, and individual concept. These will be referred to as pure, emulated, and individual, but keep in mind that these are all still representative of concepts, and none are more divine than the rest.
Pure gods are of pure concepts - tradition, happiness, solitude. These are often old deities with many true believers, though not all will realise that. They are the broad concepts with often no direct physical form in the material planes.
Emulated gods are often of objects, events, or other significant happenings in a certain plane, for example, day, storm, dark. These deities are of varying ages, but mostly ritual following - most are not True Believers, as few people genuinely want to be like a storm. However, many will offer rituals in the hope of winning the slight favour of the deity, or out of admiration.
Individual gods are perhaps the strangest. These form from two sources - either someone caring immensely about another person, due to a close bond, or the person making a significant impact on their life, or they form through admiration or jealousy, the desire to be that person in every way possible. With either method, a mortal cares about an individual above all else, and so a deity is formed. They are almost always newborn or very young, with very limited power. The First Believer is the only true believer - the individual the only kinperson, and it is very likely that these might remain the only two followers. However, despite these gods being weak and quickly forgotten, they do exist, and so are worthy of note.
Gods do not have certain mortal qualities - gender, a name, a physical form. Their existence is of pure consciousness, uninhibited by that which is required to entirely become part of a mortal plane. However, with enough power, they can influence more and more of the mortal plane they were born from. They are known by the ideal they represent, and by titles meaning the same. For example, a deity of the dark would be known as Darkness as the closest to a name that they have, but also possibly by The Pitch, The Welcome Void, or other titles of similar vein.
A newborn god has very little influence over mortal planes. They may communicate with the First Believer and subsequent believers (though often less clearly while still very young), but often cannot influence the mortal plane directly. They are also able to give a little of their power to mortals. This can create semi-divine mortals capable of great power, with different deities forming different classes. After all, a god of rage can inspire the power of a barbarian but not a druid, as they are connected to where barbarians draw their strength - brute anger - rather than nature. This isn't always intentional on the part of the mortal - it is simply a god recognising and aiding their own. A mortal can in fact be a true believer of an entirely different deity, but gods can still affect them if they are powerful enough - a kinship is all that is necessary.
Powerful deities may control believers or even followers of other gods, and even create a form for themselves in a mortal plane. They can communicate and instill power into even the unwilling, and wield great power over objects linked to their domain in mortal planes. Precisely what a deity will actually do depends on the entity, how involved it is with the affairs of mortals, and how many other believers it wishes to attend to first. It may remain entirely uninvolved, or help a select few, or try and aid any who call upon it, true believers or not.
Gods may also interact with each other once they have gained enough strength. They may only be pure consciousness, but they can communicate through their believers. The interactions of their true believers shapes their relationship with each other. For example, if the followers of a night god and a day god are opposed to each other, seeing each other as opposites, so will the deities themselves, and they may then use their influence to work against the aims of the other deity or their followers. On the other hand, if the followers of each see the other as a second half of a whole, a harmony, then the deities' relationship will reflect that, and they may even work together.
The physical form a deity will take when creating a form for a mortal plane is often representative of the deity, but is subject to change every time they leave and return. They often use the same form when they talk to an individual repeatedly to avoid confusion. The form also tends to be humanoid, as it makes communication easier and it is easier for mortal minds to handle. However, the only limit is power. A deity can take any form they wish, whether that be huge or tiny (though large and complex ones take more power to keep animated and in existence). There does tend to be a time limit, which depends on the size and complexity again, as it takes strength to keep something both in existence and animate. A large form will have to be removed from existence in less time than a humanoid.
Mortals and Gods
Mortals and Gods can have a variety of relationships. The power a deity can offer, the connection with their plane that a mortal possesses, or simply the understanding of the other. Humans have the wide array of deities available, whereas gods have five types of humans - the First Believer, true believers, followers, kinpeople, and those that are unimportant.
The First Believer, as explained earlier, is the person whose ideal is formed into a god. They have a closer connection to them, as the deity is of their specific understanding of this value, and the deity finds it easier to communicate with and influence the mortal. True believers are those who come afterwards - people who also worship this god, whether they are aware or not, those who seek this god as the most important of things in their life. Followers are those who actively choose to worship the deity through ritual. They may not be true believers, but they are still free to perform rituals for them, and the deity is still aware of them. Kinpeople are those who invoke the deity often - they may not be true believers, but the value of that god is still important to them, and so they are still acknowledged by the deity. After all, a god will necessarily be aware that their domain has been accessed, even if that person doesn't worship them as such. Finally, the rest of mortality is what remains. These people have no connection to the deity in question, and are simply anonymous inhabitants of the mortal plane from the god's perspective.
A notable thing that deities can do is give power, and this is where the concept of Classes came from. Each class derives their power from a deity, whether they are aware of it or not. As the mortal uses their newfound strength, they become more tied to the deity, a closer kinperson, and so the connection is strengthened and their power can be increased. In addition, any use of the power counts as a ritual in the name of the deity. Some classes work a little differently to others, and they shall be explained here.
Warlocks can be true believers of any deity, whether it is the specific one they derive power from or not - to become a warlock, all that is required is that the mortal has a way to contact the specific deity in question. Often this comes in the form of the mortal being a kinperson already, but it can also come from simply being a follower, even a single ritual to open the connection. Regardless, once a mortal has become any class and they use that power, they become a kinperson if they weren't already. Warlocks are the only class that seeks out the power of their own accord, and due to this, the deity often requires a catch of sorts, to make it a fairer trade. After all, they have no need for a warlock, but they may find a way to work it to their advantage.
Clerics and Paladins are kinpeople of any deity, provided they are also followers. They need to make an active committment to the god, and then that is rewarded (or perhaps punished) by the deity offering them power to do more works in their name. Whether cleric or paladin is the class depends on the strengths of the person and the whims of the god, but only the paladin is bound by oath to continue to serve the deity.
Sorcerers are what is created when a deity takes a human form and has a child. The physical manifestation of the deity is inherently divine, as it is animated by divinity, and this is passed on through the genetics to the child. They tend to be true believers or kinpeople, due to the inherited link, and often have some subtle physical traits linked to the deity, such as the slit pupils of a dragon. When the divinity is indirect, for example being the child of a sorcerer, the power isn't strong enough to be projected outwardly, but the physical traits on occasion are passed down. Their power derives from the innate divinity within them - the god, whether aware of this or not, did in fact gift some of their divinity to the child.
All other classes are kinpeople of any deity, whether they are followers or not. They are chosen by the deity, sometimes asked and sometimes not - but who would turn down the offer of power with nothing in return? The specifics of their power depend on the deity in question. A deity of the arts would create a bard, one of stealth a rogue, one of spirituality or physical and mental harmony a monk. These are mostly categorised for functionality rather than origin, and the actual manifestations of the power can differ greatly.
When multiple deities take an interest in one mortal, this is known as multiclassing. A mortal can accept power from multiple deities, however, they must balance how closely they are tied to each. In addition, a mortal can only contain so much divinity. This means they can only accept a certain amount that must be split between all deities that have given power, gaining versatility at the cost of raw strength in one.
Rituals and Worship
The way the gods are worshipped varies greatly. The major distinction between methods is rituals vs worship. Rituals are actions performed in the god's name, actively chosen, and they can be done by anyone, not just true believers or kinpeople. Worship is holding the value of the deity highly, that which true believers do whether they realise or not, and which kinpeople do to a much lesser extent.
Most people actively perform rituals for certain gods, but this may not be the one that they worship. Knowing which god someone is a true believer for takes great knowledge of self, or the deity telling them actively. Knowing the deity that someone is a true believer of is knowing the value they hold highest, and is a great insight to that person. Some people go their whole lives never knowing, and others know from very young. Occasionally, a person will change from worshipping one deity to another, and this marks a great change in their self, but this is reasonably uncommon, though not unheard of. These people tend to know they have changed to be a true believer of another, and depending on the cause of the transition, may still perform rituals in the name of the old deity as a form of respect and gratitude, or may avoid them entirely.
There are two common locations for rituals - shrines and temples. Shrines are often created by a household or an individual within it, so that they may have a designated place to perform rituals at home. These often have some places to burn incense, or candles, or a mat to pray - general paraphernalia for individual rituals. They also often have an object, image, or statue to the specific deity. Temples are buildings for public rituals, again dedicated to a specific deity, and they will have dedicated followers that help with upkeep of the temple and management of festivals and suchlike. If someone wishes to perform a ritual for a deity that there is no shrine for at home, they will often visit a temple. These are simply shrines on a larger scale mostly, with iconography of the deity, decoration, places for group ritual and places for individual ritual. Sometimes, a shrine will be created outside of a house. It is still a place for individual ritual, but they tend to have someone watching over it and making sure there are resources for ritual available there. These are less well-known for those who don't live close by, but not uncommon to stumble across.
Common rituals include making offerings, burning candles or incense dedicated to the deity, using gifted power from the deity, prayer, ritual music or dances being performed. Technically any action performed to be a ritual is one, but often certain ones are common. Particularly with older deities, tradition forms specific rituals that are common. Additionally, for older gods, festivals can form - days set aside to celebrate that god, which offers many rituals to them due to many people celebrating. There can also be smaller, regional festivals in certain areas for smaller deities, especially where there is a temple nearby.
Some Example Deities
Wealth
Classifications: old, pure concept, large following of both true believers, followers, and kinpeople
Wealth, also known as The Comfortable Luxury, is an old deity, older than money itself, old as when humans began to store things and give them value. They were born of a poor woman with very little, whose entire life had begun to revolve around earning enough to keep her alive. From this desire for luxury, to not have to work, to be able to not worry about money, from her fantasies of riches, Wealth was formed. This woman has long since died, Wealth quickly growing strong enough to help her to a modest financial situation before she passed on, and Wealth has been a strong and well-regarded deity ever since, with many temples and shrines. Many still seek wealth, whether they need it or not, and so Wealth continues to provide.
Rebellion
Classifications: mature, pure concept, a fair number of true believers and kinpeople, but few followers
Rebellion, also known as The Bane of Oppression, began to exist when society started to form hierarchies that began to oppress those it governed. They have few followers, but those that do are dedicated and appreciate them. Rebellion has always been very involved in mortal affairs, aiding the revolutions of the world both violent and subtle. They tend not to get along with Tradition. They may not have a temple, but shrines can be found in the households of those who reject the society they find themselves in, who wish for freedom.
Night
Classifications: old, emulated concept, Ritual God - few true believers and kinpeople, many followers
Night, also known as The Pitch or Home of Stars, is a very old deity. They rarely interact with mortals, preferring to remain eternally other, separate and unreachable, yet consistent, as consistent and yet distant as the sun being replaced by the rising moon every night. Many offer rituals as a mark of admiration and respect, and some in the hopes that night will come gently or be a protection. It is very rare that Night responds to their followers, but when they do, it's often someone rather unique who will shape the world, as night shapes it from day.
Faeranduil Naenan
Classifications: newborn, individual concept, a single True Believer and a single kinperson as the two followers
Faeranduil Naenan was formed after their mortal namesake saved the life of a 9 year old child, Clara. The child was being attacked by goblins, and witnessed Faeranduil incapacitate them with virtually no effort. They then vowed to themself that they wanted to be like Faeranduil someday. When they realised they had created a deity, they informed the mortal Faeranduil, and they both decided to offer rituals to it sometimes, since they both felt responsible for their existence, and while Faeranduil the god isn't very powerful, they still do what they can to aid them both in return.
Notes for usage
The classes explanation isn't required, and can be removed very easily. If you just want to keep paladins and clerics and maybe warlocks, that's chill, go for it, it's really up to you.
You may notice that this then ends up with thousands of gods, and you'd be correct. You don't need to come up with them all, and that's arguably an impossible feat, so just create the ones you need and the rest can be left to the imagination.
This is a tool that can be used however you wish - it isn't limited to D&D, I just used it as a vessel to explain all this. It isn't limited by world, species, dimension, anything. Use it wherever you'd like, change it however you wish - go wild.