Protagonism is a religion with no god, no holy books, no clergy or leaders, no prayers or rituals, nothing like that - only a moral system and philosophical tenets. The centerpiece of the religion is not a belief at all, but a choice: the choice to tear down everything you only believe because you were raised to and serve your own conscience instead.
One's own conscience is by definition the highest authority for morality. A lot of people think morality can be derived purely from reason and will object to this kind of moral system with something like, "why do you think X is a sin / moral duty?" or "You have an unfulfilled burden of proof!". The truth is that these objections show a fundamental misunderstanding of either morality or reason. To illustrate I'll play devil's advocate: why is it wrong to steal? There are a few possible responses I can think of, but none of them actually answer the question.
"It's wrong because it deprives other people of their property without their consent" (deontological answer). In that case, what's wrong with depriving others of their property without their consent? Who says that's evil?
You could take a Nullus Maximus-style position here and say (he later extends this argument to cover property), "The starting point for all of libertarian philosophy is self-ownership; each person has a right to exclusive control of one's physical body and full responsibility for actions committed with said control. Note that in order to argue against self-ownership, one must exercise exclusive control of one's physical body for the purpose of communication. This results in a performative contradiction because the content of the argument is at odds with the act of making the argument. By the laws of excluded middle and non-contradiction, self-ownership must be true because it must be either true or false, and any argument that self-ownership is false leads to a contradiction."
But there's a painfully obvious missing step here. Nullus Maximus assumes that the person arguing against self-ownership must be claiming that they have a right to make this argument. But that's not true at all; people do things all the time without saying they have a right to it. If the anti-libertarian's position is clarified to be, "There's no self-ownership but since you don't seem to have any interest in forcefully silencing me I'll go ahead and take the opportunity to say this", then NM's argument no longer answers the question. It doesn't even need to be that radical. If the anti-libertarian says, "Self-ownership is a privilege conferred by the government / by God, but right now both of us have it", that also blocks NM's argument.
"It's wrong because it's selfish/cruel" (virtue ethics answer). In that case, what's wrong with being selfish or cruel?
You might argue: "Being selfish or cruel is morally evil". But that's circular. I asked what's wrong with it, and 'morally evil' is a direct synonym for 'wrong' in this case. You were able to make the first jump because at least selfish is a word that can be given a clear definition and there's no way to deny that enriching yourself at the expense of others fits that definition. But you can't make the jump from selfish to evil because 'evil' doesn't have a non-normative definition, so you're forced to say "it's evil because I say so".
"It's wrong because it causes suffering" (consequentialist answer). But what's wrong with causing suffering?
The point is that there is no why. All reason can do is go from one proposition to another that it entails, and for factual matters this is fine because we get factual information to start with from sensory experience; but statements of fact alone can never entail statements of morality. So to get our moral system started we have to get a foundation from conscience.
I'll describe how this process works. Conscience is a built-in mental faculty all people have that judges possible actions from the person's current situation. From these case-by-case judgements, there are two ways to derive a moral system:
Through instinct. This one happens automatically and subconsciously. Our instinct forms a system of assocations that allows us to try to predict what our conscience would say for a situation we're not in. This is the same way people often have sense of how a practical science experiment will go without consciously knowing the underlying principle. But, due to the inductive nature of this process, it cannot be 100% reliable.
Through reason. We can use reason to extrapolate what the underlying "rules" of morality must be. This process is actually exactly the same as how science is done: you get data points from a non-rational source (experiments or conscience), and then use reason to connect the dots and figure out how it works (this is still inductive and therefore not infallible). This one requires conscious thought, but is more useful, since it allows us an understanding that is not possible through conscience or instinct alone, so that we can discuss our system with others and debate about it. Since morality must be consistent, pointing out an internal inconsistency in a rational person's extrapolated moral system forces them to reconsider it. Reason can also use hypotheticals as data points (and has to because no human has been in enough situations to fully derive a comprehensive moral system), but hypotheticals are judged by instinct, since conscience can only speak on a situation you're actually in; so this is less reliable.
Conscience itself, though, must necessarily be infallible because every other source of moral judgements is flowing from it. Arguing that conscience is not infallible is the same as arguing that the source material for a work of fiction is not infallible on the canon of the work.
But, just like reason in its domain, the accuracy of conscience depends on having the correct inputs. Of course an infallibly wise person could be 'wrong' on a practical judgement if you lied to them about the facts of the case. Conscience, similarly, depends on being fully aware of how everyone involved will be affected by a given action. For example a newborn likely doesn't realize that the other people around them have feelings like they do, and so neither they nor their consciences are to blame if they act selfishly. Hypotheticals are even more so. Since you're not actually in the situation, your mind might fill in some details the statement of the scenario left out (eg. that one of the people involved who did something bad was repentant), and if you didn't realize you were doing this, you could get a bad reading from your instinct on what your conscience would say. I catch myself doing this all the time.
For the purposes of merit and blame though, conscience is infallible without any caveats (just like reason), because of course you can't be at fault for doing what you had no way to know was wrong.
You might ask me at this point whether I believe that all people's consciences are in agreement. After all, if I didn't then noncontingent morality (the requirement that the correct moral system is the same for everyone) would be broken. My answer is an unhesitant yes. Everyone's conscience is infallible and operates according to the same underlying principles. I need to point out that there's an apparent inconsistency in such an objection: no one seems to deny that what is logical or rational is the same for everyone (provided they aren't misinformed), and we make that judgement using our own individual reasoning, a built-in faculty just like conscience. Why does nobody think it's a problem that this means either everyone's reasoning is the same or noncontingent rationality is broken?
But even besides what I've explained about needing the correct inputs and having to go through instinct for hypotheticals, it might seem that people can be wrong about morality while listening to their conscience. This is due to the further complication that most people aren't even talking about the same thing I am when they say "conscience" or even "morally good". We were all trained to observe certain rules as kids - don't hit people, don't steal, don't be mean, don't break the law (note that all of these rules are at least missing two exception clauses) - and told that these behaviors were what the word "good" meant. So now all of the morality-related vocabulary in most people's minds has been corrupted to refer to this preconceived system instead of the actual voice of conscience. When most people ask their "conscience" whether a given action is "good", they're really asking their instinct whether the given action is in accord with the system they already believe in - because that's what they've been told these words mean. It's not easy to tell them the real definition of conscience either, because if you just say "it's the voice that tells you what's right and wrong", they think, "Oh, it's that thing I'm already using", but they haven't actually internalized what you were trying to convey.
Anyway, most of that was a tangent to refute objections. The point is, reader, almost everything you believe about "morality" is probably coming from this indoctrination. To be a good person, you have to knock it all down and follow your own conscience. I can only beg you to give it a chance.
The religion's name might be starting to make sense to you now. It's based on the sentiment that each person should be the protagonist of their own story and that making it a good one involves being a good person.