"Ethics and morals" are constraints on your ability to succeed. The _objective_ value of commiting an immoral act is easily determined. The costs are not. They can be summarized as the change in value of how others perceive your 'character' (and how that would ultimately effect your life) and a 3 part product as follows: 1) probability you place on their being an afterlife. 2) probability of a particular action resulting in negative consequences thereafter and 3) the value you place on those consequences, presumably negative. There are other _subjective_ values, but it's not necessary to give them any consideration given where im going with this (ie: cognitive disonance from contradicting established values you hold). Similarly, if the concept of non-utility based values for doing the 'right' thing were accepted as true, it would be consistent with what follows.
The problem with a "hell" is that it ultimately places an infinite negative utility value in the third column. That means that, so long as you have even the faintest suspicion of their being a biblical hell, if you were to act rationally (in the philosophical sense), you'd have to abide by every moral and ethical guideline you set out, absolutely ... since the product of three figures, where one is infinity would still be infinite.
Given those premises, for any immoral action resulting in an expected return on utility, the relevant costs in terms of expected loss in utility for the future would have a negative value... in the sense that, a value in utility for your life time is finite (constrained by your life expectency) and the potential loss in utility in the afterlife will always be far greater, so long as you have even the faintest of feelings that there may be a hell where "sinners" rest for eternity.
It's understandable that if you were to actually calculate the costs and benefits of each immoral action you would need a discount rate for the future, but it would still ultimately be dealing with finite numbers relative to infinite numbers. Additionally, presumably there is an immeasurable loss in utility for a given unit of time spent in "hell", or at least we expect this to be the case to some degree of certainty. This is in comparison to the status quo -before giving consideration to the alternative course of action, namely heaven, which would lead to limitless utility. The rational decision would always bend in favor of doing the "right" thing.
What we can conclude from this is that people who act contrary to their own morals are either irrational, or they have zero belief in the existence of a hell. Given that everyone, or close to everyone has acted in a manner that they would regard as immoral at some point, the vast majority of the population would fit under this umbrella.
It's a paradox because I dont find the conclusion acceptable. I believe that everyone places some probability on the existence of a heaven/hell. I also believe that humans are essentially rational. There'll probably be a couple of dimwits saying "LOLOL PEOPLE DO STUPID THINGS ALL THE TIME". Doing apparently irrational things and being irrational are different.
edit: the ability to repent doesn't alter this to any meaningful degree, since there is always a given probability of death before you're able to repent (again, a finite number).
So basically, i can't decide what premise to reject.
err... that's not really a life philosophy so much as it is a belief coupled with a paradox. I'm probably ranting, but it'd be great if any of the competent posters out there could take a stab at it.