I just replied to a post on my blog about Buddhism and Islam. It is about the fact that the more conservative elements of Islam seek to define what Islam is so that they can point at other Muslims who do not believe what they do and call them bad Muslims. Now I am looking at Christian blogs about the difference between Buddhism and Christianity and I see the same thing - Christians narrowly defining what it means to be a Christian and then contrasting this with a superficial or wrong version of Buddhism. It is ironic that a lot of this comes from Protestant America. Protestantism was founded on the idea that people could work out for themselves what being a Christian means and the people who founded America where searching for a place where they could be free to do this. Ironically, the first thing they did was to force everyone to obey their ideas about Christianity. The first episode of the PBS series, God in America, provides a good portrayal of the actual historical events.
There is no set definition of what it means to be Christian. You do not need to believe that the Bible is literally true, you do not need to believe in heaven, and you do not need to believe that Jesus died to atone for our sins or that he is the only route to salvation. Many Christians do not believe these things. For more on this I have posted a number of christian sources