I'm not a Christian anymore (haven't been for a long time) but when I was young I went to a Church of England school and my mother was a liberal Christian/neopagan. For me, God's existence was a given, though both me and my mother believed that all religions have some truth to them, not just Christianity. The Christianity I was brought up with was a pretty harmless, feel good religion, so I never thought to question it. It was only as I got older that I started to feel that Christianity wasn't for me. I'd always been drawn to the image of Satan and the associated images and eventually I decided to go with my natural inclination towards that side.
I don't begrudge my mother's form of Christianity though (although I did for a while in my moody teenage years) since it doesn't harm anybody and encourages people to care about each other. I think the humanitarian aspect of Christianity is it's most appealing aspect and though I think altruism is ultimately misguided I can't fault the intention.