Them - "Jesus Christ was never violent!"
Me - "Who do you think humiliated Egypt because they wouldn't let the Hebrews go, firebombed Sodom and Gomorrah into oblivion, flooded the planet, and had Israel end quite a few ancient civilizations on the spot because they couldn't get the point? Also Book of Revelation."
We have to avoid being violent as much as possible and if we have to be violent then it must be out of necessity, not hatred or revenge. Only God can handle the former without going overboard and the latter belongs to Him and Him alone.