Atheism is bad for your health. How, you say? Well, it forces you to fill up your time with something other than religion. Religion is imperfect, but it gives a person some structure.
For another, atheism enables the flourishing of anxiety and depression. In a religious tradition you are supposed to put God first, never yourself. So the endless ruminating and dwelling in one’s own mind and about one’s own problems yields unnecessary self-destructive thoughts.
Then there is the absence of moral guidance. For years I argued with my conservative religious friends about who was more “moral.” I was a liberal and I was wrong. In my travels I learned that without a religion humans are deeply confused about right and wrong. Not the big things. All but the sociopaths get the big things, but we are confused about the smaller ways that we choose good and evil, right and wrong, leaving us vulnerable in the modern world.
Without religion, most of us are lost. Even, perhaps especially, if we don’t know it.