Let's get this straight

It is hard for me to square any Christian military posture toward “our enemies”—the kind of label unworthy for the follower of Jesus—with what Jesus both performed in his last week and what he teaches here [Matt 5:38–42] (as well as at Matt 26:52). Prior to Constantine, apart from a few exceptions, Christians refused to participate in the military. Their nonparticipation was no ethic of resignation to Rome’s might but an ethic of resistance in the form of creating an alternative political society, the church. Beside their obvious denunciation of the pervasive presence of idols and false religions in that military, the earliest followers of Jesus did not enter the military because they believingly thought Jesus meant business in the passage under discussion. The issue for the pre-Constantine church was killing those made in God’s image.— Sermon on the Mount, pages 130-131