Christians like some people who are not Christians, will be ignorant of the teachings of their own scriptures. Such a one I daresay is you holkapolka.
To you Jesus is the King of Peace and so you keep in mind the 5th commandment which says: 'Thou shalt not kill'. Whilst they forget that Jesus is said to be a warrior King who will fight AND wage war for God.
In the OT God commands his people to kill. Thus killing and fighting is sanctioned by God under certain conditions [Leveticus 24:17 - 'Anyone who takes the life of any human being shall be put to death.'] in your own scriptures! You may say, well the OT does not apply to us, as some people do.
Jesus is reported to have made a whip to drive the people out of the temple [John 2:15-16]. Jesus use forced. You may call it pacifism if you like, but we can see that a whip is not a tool for passivism, nor is overturning people's tables. Jesus will also be that warrior of God I said he is described as. In Revelations Jeus will wage a war in righteousness [Revelations 19:11-15] having a cloak dipped in blood. Remember, war and fighting is acceptable under certain conditions in your scripture, which you apparently are unaware of. Will you prove your righteousness [in a hypothetical situation] where your wife or girlfriend is raped in front of you and you do nothing, but offer up your daughter to be raped too?
The verse you cited was one about retailiation. Remember in Israel however, where one might have done something ignorantly and there were safe cities? Jesus is saying that likewise, you must forgive.
Clearly, not only must you study the Bhagavad Gita, you need to study the Bible as well.