It's not the Christianity that bothers me so much as the juxtaposition of President W Bush and Christianity. I'd say that for me, he sums up everything that's worst about some branches of Christianity - the things which have made some of my friends denounce Christianity altogether, and made me truly uncertain about calling myself a Christian.
I don't talk about my religion much simply to avoid misunderstandings. To sum it up in one sentence, I'm a pantheist who thinks that the things attributed to Jesus are sensible ideas. My beliefs are probably closest to those of the Quaker or Unitarian Universalist churches. I could not be further in stance from the pro-war, anti-abortion, anti-gay, fundamentalist, hatemongering so-called Christians. And yet, many of my friends think that to be Christian is to be pro-war, anti-abortion, and all those other things. So I can't use that word for myself.
I didn't see rivka's rant before I started writing this, but she says what I think only more eloquently. In the meantime, that image, and the views of that eBay seller, make me feel ill.