Note: Yes I know some people will say this belongs in the religion thread but this is a specific question and something I'd prefer to actually know I got answered for me then debated over a couple months with twelve different people. I also know that atheist is simply someone who doesn't believe in a God, while what I'm referring to is someone who doesn't believe in a life after death situation which is much broader of a term.
So here's the conundrum:
There have been multiple times where I have run across people who are atheists in the religion thread and in other sites who have essentially said "If someone has to fear eternal damnantion to do good things they aren't really good." or the other common one "Why should you have to get the promise of heaven to do good works."
Now, to memory, all these people didn't believe in an afterlife or a soul. Essentially completely in disbelief of the supernatural. So if I put myself in the shoes of someone with those belief's I come up with this scenario: If there is no God, no Hell, and no Heaven, or even any form of life after I die, what is the point of having any form of moral compass? I can do whatever I want as long as it benefits me more then it harms me throughout my life, since after I die I won't have to worry about anything.
There is also the fact that with these same belief that there is no afterlife, suicide is an extremely appealing option for people of high stress levels and depression. Heck I'd have probably done it as a child if I wasn't Catholic, either that or someone else would have died. The other possibility was that I'd do as I mentioned in the scenario which is simply do whatever I found convenient, if that meant manipulating people into doing what I want then that's what would happen. Fortunately it didn't, but it was a plausible scenario.
I simply do not understand where a moral compass is if an individual does not believe in an afterlife of one form or another. So for any in that situation please enlighten me to your reasoning. And even if you aren't in that same situation, if you think you figured out their reasoning, please tell me anyway. Could be useful for an extra view.