Christian violence is in some cases not only acceptable but required, because it follows God’s direction and example.
Reasons and examples include self-defense/defense of those unable to protect themselves (cf. Luke 22:36 and much of the Old Testament); Our Lord beating and whipping the money changers in the Temple because they profaned a holy space- in other words God Himself used human violence against another human for disrespect of the Father. Battle of the Milvian Bridge, The Battle of Lepanto, the story of Jeanne D’Arc and other Divinely assisted military actions in post New Testament times. Finally the defense of the innocent is at times a required duty. A short time ago there was a school shooting in Florida. The police remained hiding behind their vehicles while children were slaughtered. This is an example where failure to use violence is a grave sin.
Pacifism is your right and in many cases is willed by God (think of the nuns of the Vendee, or St Francis walking into a muslim camp) but sometimes it covers a cowardice or dereliction. We are judged by what we do with what we are given. Pacifism that impacts only your life is one thing- pacifism that is contempt of the lives of others is another matter. God knows and judges the heart.