well the thing is, jesus DID blatantly contradict many things that were taught in the old testament, and most christians who know what they're talking about will say that those are the teachings they believe they are meant to follow. i'm christian, (in a vague, very personal sense) but i don't believe i have the right to impose my beliefs upon others. i find some things that others do morally objectionable, and i will openly admit it, but i don't accept that such a fallible piece of doctrine has the right to determine the rights and responsibilites of an entire community/society. if we were all christians, every single one of us, and never faltered in faith, and followed the new testament down to the letter, then my opinion might change.
just a little food for thought though (re:interpretation of the bible, its infallibility etc... I just found it interesting considering a lot of people, me included, tend to cry "but it's all ambiguous!":
"Knowing this first, that no prophecy of the scripture is of any private interpretation" 2 Peter 1:21 KJV
and in another version:
"Above all else, however,remember that none of us can explain by ourselves a prophecy in the scriptures. For no prophetic message ever came just from the human will, but people were under the control of the holy spirit as they spoke the message that came from God" 2 Peter 1:20-21 GNB