Would you have helped Herod kill all the babies? But this is an interesting thought. Had pro violence Christians not helped Hitler enmasse, and followed the Sermon on the Mount instead as I and few others do, Hitler would not have done anywhere near the damage they helped him accomplish.
When Jesus said to turn the other cheek, it was the same thing as the Old Testament verse about "vengeance is mine saith the Lord." It did not mean we are not allowed any self-defense, though. If you think that is what it means, then how would you reconcile it with Luke 22: 36-38?
The Lord delegated "vengeance" to the law.
Even today, although we are not supposed to get revenge a la the Hatfields and McCoys, it is within our law to defend ourselves against an intruder in our homes if our lives are threatened.
When people traveled in those days, they traveled in groups, some armed with swords. It was common for travelers to be set upon. This is the historical context for the below:
Luke 22:36-38 King James Version (KJV)
36 Then said he unto them, But now, he that hath a purse, let him take it, and likewise his scrip: and he that hath no sword, let him sell his garment, and buy one.
37 For I say unto you, that this that is written must yet be accomplished in me, And he was reckoned among the transgressors: for the things concerning me have an end.
38
And they said, Lord, behold, here are two swords. And he said unto them, It is enough.