Atheists often claim to be more rational than theists. They claim to base their lives on reason rather than faith, but they don't. What reason, for example, does an atheist have for arguing that we should preserve the earth's beauty and resources for future generations? What reason is there for caring what happens to the earth after we are gone from it? Would it be immoral for the present generation to use up everything and leave nothing for those who come after? Why, on the assumption of atheism, would it?
According to the atheist all we have is our own life. There's absolutely no reason why we should care about anyone else. We may care about others, of course, but if we don't why is that wrong?
The atheist may respond that we shouldn't leave our descendents bereft because we wouldn't have wanted that done to us. Of course we wouldn't, but that's no reason why we shouldn't do it to someone else. In other words, if there is no God, there is just no reason why we shouldn't live for ourselves. Atheism can give no reason why egoism is wrong except to say that it just is.
That doesn't sound to me like a very rational reason.
RLC