It is often said that Christians cannot fight back, nor should in order to be good Christians, but this, like most of the modern liberal narrative on things they hate is nonsense based on historical illiteracy.
For example: ‘For he is the minister of God to thee for good. But if thou do that which is evil, be afraid; for he beareth not the sword in vain: for he is the minister of God, a revenger to execute wrath upon him that doeth evil.’ – Romans 13:4
See Saint Augustine’s (354-430) ‘City of God’ and Saint Thomas Aquinas (1225-1274) for commentaries on just-war theory under Christian traditions, scripture and ethical law. Also see jus ad bellum (the right to go to war) and jus in bello (right conduct within war). It is true that certain sects of Christianity do not agree with these codes, but to say that Christians in general cannot fight nor protect themselves is nonsense.