Are the Crusades Proof That Christians Are Evil?

Questions about how to respond to someone who says the Crusades are proof Christians are evil, the facts around the church burning people at the stake for saying the world is not the center of the universe, and whether that history damages the witness of the church.

• How do you answer someone who says the Crusades are proof that Christians are evil?
• What are the facts around the church burning people at the stake for saying the world is round and not the center of the universe? Does this prove the unreliability of biblical authority and damage the historic witness of the church?