you can understand what is in romans without reading it. basically people have different value systems but everyone has messed up based on what they know is right. but when paul says you are only held accountable for what you know, he refers to "the" law and not "a" law. but i think “the law” could also include science and be broader so it is one law. but our knowledge is partial anyway so if people want to view it all as different belief systems they can to some extent but everyone has violated their own belief system.
but the question is, what if people have a belief system that is all bad. well wouldnt violating that be like saving faith. like they are bad but made a mistake and were accidentally good one time. well people say being good one time isn’t faith. it is just a random act of failing at the destruction you wanted to cause. so that is the doctrine of total depravity. if there was something that seemed good after all then the person finds out how to make it a loss by their final rejection that is like an ingratitude so bad that it would cancel that inconsistent moment anyway. that is my guess about it though really i would suspect that the mistake to be good would catch everything else on fire, destroying the evil and leaving only a saved soul who loves much because they have been forgiven much.