Truth of the Bible is good to share and defending the faith is good, too(but defending myself as a Christian tends to come off bad). For example, Matthew 5:38-42 speaks of how to handle a circumstance when one is insulted(a slap would be considered an insult to a Jew similar to someone spitting in the face). Romans 12:17-21 is a cross reference to the Sermon on the Mount in which those of the Kingdom should expect persecution as part of the saving package. LOVE! Discuss the subject matter and truth of Scripture and pray for the one persecuting with words(much nicer than spit, I think). Our struggle isn't with individuals in this instance...it is spiritual warfare and handled with the armour of God. When can you remember Jesus ever being what some would call verbally "rude"? to those needing Him...maybe to the spiritually elite Pharisees(righteous on the outside and open stinky tombs on the inside). Accentuate the positive by turning the conversation to Truth...you never know, maybe someone persecuting will be saved thru grace and mercy(because the persecuted is yielding). I'm not much for ignoring someone unsaved so I can float merrily along in a fishbowl. I do find that when I'm most loving and definite on Truth, they might avoid me in an attempt to sidestep Christ reaching out to them thru me. : )