I have renewed faith when I see Christians (like Rob Bell, the OP, etc.) making this point.
They seem to understand that the reason that people aren't stopping for the pamphlet or listening to the man is not because the world is evil, or that they have hard hearts, but because the man isn't a good witness.
One would think you would figure that out simply by praying to God and listening to the Holy Spirit, but if you think you have to win over "the enemy" and think that you can talk, but refused to listen, you probably can't hear God either.
Many posters here will talk of how Jesus was harsh, quoting passages where he spoke to the Pharisees. The Pharisees? Really? The people in the temples that preached the Scripture, and were thought of as holy by the people of the towns?
Jesus wasn't standing on a street corner, telling the tax collectors that they were theives, and telling the prostitutes that they were going to burn in hell. He loved them. He ate with the "sinners," and if he was eating with them, I assume that he just talked to them as any friend would, not simply preach to them, then want nothing to do with them. They were drawn to him. So if people are repelled by you, it's not the lame excuse that is usually used ("many people rejected Jesus too!) but it might be that you are a bad witness. You may be lacking in love. You may have no love in your approach.