What does The Bible say about defending yourself physically if you are attacked without provoking the attack?
"Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also. And if any man will sue thee at the law, and take away thy coat, let him have thy cloak also. And whosoever shall compel thee to go a mile, go with him twain. Give to him that asketh thee, and from him that would borrow of thee turn not thou away." (Matthew 5:38-42)
For years it has been argued whether there are any limitations on what Jesus said here. Some have come up with the concept of "turn the other cheek, but after he strikes that you are free to strike back." Others say there is no justification for a Christian to be violent under any circumstances, not even to save the life of himself or another. Most of us, I think, take a position somewhere in between.
Paul was willing to use the might of the Roman army to protect himself from those who were plotting to kill him (Acts 23:12-33). Others were willing to give their lives when they were persecuted for their beliefs. Whether they would have done so when persecuted for other reasons is open to argument. There were soldiers who were Christians and did not give up their profession.
It is a hard question which each person must decide for himself. Should the words of Jesus bear all the weight, or are they merely the ideal. How much weight should be given to Paul's defense, or the lack of defense of the martyrs? If I make a decision for myself based on the scriptures given, and if it is the wrong decision, God can forgive me. That doesn't mean I can fight back in violation of my understanding and expect God to forgive, though.