As a rule, Christians do not in the least reflect Christianity. We are a group of self-professed sinners who (should) try our best to defeat our sin. Jesus Christ is the model we strive to emulate, but our sin keeps us from achieving that; only his death on the cross makes it possible for us to have hope of salvation, as God sent him as a human sacrifice, flawless in every way, to take our place in death that we might be saved.

So yes, Samat, Christ is the center of Christianity, but the Bible is the only way we can know about him and understand what he did. The Bible is not in the least a nasty book, it's a book entirely about how we as humans have utterly failed God and yet he still loves us so much that he sent his son to die in our place; it is a book about love that we don't deserve.

Christians very often do un-Christian things in the name of religion. It's our attempt to do what is "right", but it all too often goes to the extreme and ends up doing the exact opposite of what we were intending to do. That's the fault of the Christians (sinful people), not Christianity, and is the result of us letting our sinful nature and self-centeredness take over. People doing things in the "name of Christianity" should never be mistaken for Christianity itself, as there's no way any person can sufficiently reflect Christianity, we can only try (and fail miserably).