Of all the things which rightly make an atheist an object of pity, the one I feel sorriest for the atheist for is when he realizes that all pleasure, satisfaction, and joy that he experiences is (according to him) nothing more than some chemicals in his brain. For two main reasons:
First, because he then accords Joy no significance. When this happens one can almost hear the sound of the cell door slamming shut on the mental prison in which he is trapped. It is a prison with no windows and no sunlight can enter it.
Second, because he will soon notice that there is, therefore, no distinction in kind between real happiness and what is produced with recreational drugs. And recreational drugs—the hard-core ones, I mean—are basically a form of slow suicide. (Not because their side-effects cause death, but because their main effect is basically a temporary suspension of living in a haze of mere feeling.)
There are many things for which to pity this atheist, but this one has always affected me the most. Once the door of this mental prison has been shut, I do not know of any natural force which can open it. I doubt that there is anything to do for a person in such a case but pray for them.