Sure you can be a Christian and a Democrat at the same time. But can you really be good at either one if you are both?
You have to sacrifice so much about Christianity to be a true democrat. And you have to sacrifice what it means to be a democrat if you are a true Christian.
The modern liberal democrat(Is there such thing as a non-liberal democrat) is a cancer on America. The core values of the modern democrat is the absence of truth and the tolerance of any and all stupidity.
Republicans are no saints. But democrats are so far removed from a life of faith in Jesus Christ and his actual teachings that it's almost essential to never go farther then a Unitarian's belief with their faith.
I'm still a republican. If only to make sure no one mistakes me for a democrat.