I cannot think of a single passage in the New Testament that justifies man-made prejudices (and that can stand up to scrutiny). Being of the "evangelical" persuasion, I do not hear man-made prejudice being preached or condoned. Jesus is about breaking down man-made barriers, not fortifying them. We also have to remember, that while He spent most of His time with "sinners" - He remained sinless. But sin has little meaning to non-believers. It is only when the purity of Christ enters into our being, and we have a regenerate spirit, do we truly understand the consequences of sin.
What I hear, and what I hope to one day preach - is that the only way to know God is through a relationship. You can know OF God, you can know ABOUT God, but the only way to KNOW God is by having a personal, active relationship with Him.