True Christianity is intolerant in the sense that it holds to the absolute that Christ is the way, the truth, and the life, and none can be saved outside of him.
True Christianity is, on the other hand, the most tolerant of all religions. The Christ-like refuse to use any form of persecution or coercion to advance the borders of the kingdom.
When the world sees the preaching of the gospel as a spiteful, vengeful crusade against others, they will react accordingly. Sometimes they perceive the gospel in this way because those who preach it are spiteful and vengeful.
At other times they perceive it this way because the god of this world has blinded their eyes.