I think people are overly sensitive. Or maybe I have thicker skin. Not sure.
I know for a fact that when I decided to not believe in the existence of God, I allowed myself to do all kind of crazy stuff because in my mind there were no consequences and no one to hold me responsible. From one bad choice to another, worse and worse, until I was so lost and my mind was so confused, I had to fall down on my knees and ask for Love. I can see so many changes in my life. I just feel better, overall.
All I'm saying is that I agree....living a life where you really don't care about what's going to happen after you die, can lead to multiple issues, and if they get bad enough, your mental health will definitely be affected.
I'm not saying atheist are atheists because they are mentally ill. I'm saying atheists can end up having mental problems.