If I had exactly one objection to pick about Christianity, it would probably be Christ as the last prophet. The most important, the final prophet; these things would be reasonable. But the last? A prophet, biblically, is someone who argues with God and wins. We still need that.
The literary value of the old testament is greater than that of the new. The new testament really only becomes profound when you take that lens into the world with you. The old testament is profound when you bring the world to it. The NT is something other than literature really.