This quote, popularly (but incorrectly) attributed to Marcus Aurelius, proposes indifference to religion:
Live a good life. If there are gods and they are just, then they will not care how devout you have been, but will welcome you based on the virtues you have lived by. If there are gods, but unjust, then you should not want to worship them. If there are no gods, then you will be gone, but ... will have lived a noble life that will live on in the memories of your loved ones.
But this raises the question — what if you fail to live a truly good life, in the eyes of the god(s)?
The gospel — literally, the good news — about Jesus is that indeed we all fall short, but God sent Jesus into the world to take the punishment that we deserve, and through him we can receive forgiveness.
There is, of course, a catch. We have to accept that forgiveness, and that requires taking Jesus seriously. Thus psuedo-Aurelian indifference breaks down.