Frankly, and all due respect to people who find solace in religion, expecting a god to reward you for ethical behavior is how you get into this warped frame of mind in the first place. It's a lot easier to understand ethical behavior being a neutral, not-correlated thing to wellbeing without bringing a deity into it at all.

Which then frees a surprising amount of mental and emotional bandwidth to wrap your head around all the very good reasons ethical behavior is still the better option, frankly.

Even if there was a god, and even if it was the god of the bible this would hold up. Surely you're in a better position by Christianity's values if your ethics are unrelated to worldly rewards of any kind. Being rewarded postmortem sure sounds like a bit of a scam to me, but it seems to necessitate the exact same ethical framework as a world with no god. Which I don't think is accidental, but has the advantage that we don't need to agree on the existence of a god to agree on what ethical behavior looks like and why it's... well, ethical.