What about "turning the other cheek"?
After seven years of teaching Christian Martial Arts, I have been asked this question a lot. The word of God does say that if someone strikes you on one cheek, then you should turn the other cheek to them. I teach and expect my students to do just that.
Now for some clarification. In Jesus' day, to slap someone on the cheek was a form of public humiliation. It was also an offence for which you could get sued. If someone insults you, in public or in private, this is NOT an action which requires a physical response. A slap in the face is not a dangerous attack and you are not harmed (physically) in any way. To react physically by launching a counter attack (even if they might deserve it) is wrong (where would we be if we were given everything that we deserved? We would all be on the fast track to hell). This would be an act of revenge, and against the teachings of the Lord.
That being said, I don't believe this passage says that we have to be a victim. I don't even think the word of God implies that we can't physically defend ourselves. If that were the case, Christians couldn't be police officers, soldiers, security guards, or any other job where you might run across someone who is violent. We can defend ourselves, we just have to do it in a Godly manner. We only use force when it is absolutely necessary. We only use the amount of force that is absolutely necessary. We never strike out at someone in anger, or as revenge. If we do have to use force to defend ourselves, after you are safe, it is your responsibilty to make sure the person who attacked you gets the medical attention they need. You cannot leave them bleeding and broken in the street.
We are to love our enemies. We get them the medical attention needed and call the police. We can even try to visit them in the hospital or jail. Let them know that you forgive them for what they did to you, and ask them to forgive you for what you did to them. Your Christ-like love and attitude may open the door for you to share the Gospel with them. Then you have really done something to help them.
"If you're a Christian, why do you study Martial Arts?"
"Because, not everyone is a Christian."