I was having a conversation with a self-proclaimed ex-Catholic-cum-Satanist who was obsessed with the destruction of Xianity. It wasn't enough for him that it is already an outdated and dying religion and that he was supposedly free from it. And he claimed to understand that his own continued dwelling on Xianity, he was empowering it.
I recommended to him the following exercise which you might want to try.
It's a less extreme version of an exercise recommended by Crowley and I find it very effective.
Every time you start thinking of someone or something you don't want to think about (ie, an ex-gf or xianity) I want you to visualize this:
Yourself in a guilitine and the blade dropping and chopping off your own head. And then repeat this image again and again for as long as you can.
Start this process the very moment you find your mind going onto that line of thought, before the thought completes and do it every time.
Eventually it will become automatic for you to start doing that... you will find yourself doing it before you even realized you were going to think that way.
It will symbolically kill off that portion of you that is linked to your ex, christianity, etc.
Eventually you'll find your not thinking of it any more.
[Crowley's method, for the curious, suggested carrying a blade and using it to cut yourself (instead of doing visualization exercises) and using the pain as a stimuli to train repression. I've never tried it: cutting myself doesn't appeal either to my sensibilities nor my vanity.]
_Bholanath_