Is Christianity the sum of the actions and beliefs of its adherents or a set of actions and beliefs defined by the Bible?

This question is closely related to those regarding the definition of a Christian that was also discussed on the meta site here and here . While I consider that question answered and outside the scope of this site (as discussed in Meta), it seems that there is still room for this tangent. Quite apart from what individuals are labeled as Christian, is Christianity the sum of the actions and beliefs of its adherents or a set of actions and beliefs defined by the Bible? _____ Background: I recently referred an acquaintance to an article describing differences between Jews and Christians. I (converting to Judaism) said that I thought the article pointed out important differences between Christianity and Judaism. He (a Christian) said that he thought the article pointed out the differences between some Christians and some Jews. Obviously he is correct in his observation, but, by doing the latter, the article was (to my mind) also doing the former.