Atheist friend being converted to religion?

I'm a chemist. In my spare time, I'm a ham radio operator. As a result of my highly ytical and skeptical nature as well as bad experiences with religion in the past, I am pretty much as atheist as it gets. Words can not describe the burning pion with which I hate religion, especially Christianity. I value to an exceedingly high degree the few atheist friends I have as it is with them that I can most most honestly and deeply connect. Lately, one of my closest atheist friends seems to be getting drawn towards Catholicism in a hurry. I don't feel that it is my place to try and tell him what to do, especially because his religious development was already fairly advanced by the time he let me in on it. I don't want our relationship to change and I ultimately want him to do whatever makes him happy, but I still find it terribly upsetting that someone so close to me is falling into a belief system which I personally loathe and fear might ultimately cause him to resent me. I've done about all I can to show him my support but what can I do to make myself feel better?