Does the follower of Christ have the 'right' to take a life? This has been argued for centuries, accepted for just as long, and defeated as man's wisdom, fear; faithlessness. To put the debate to rest, besides the obvious teaching that Peace proclaims, to satisfy the naysayers the evidence in loosening of peace needs to be found.
We see Christ chastising Peter when the sword was used. The argument is that Christ's chastisement was because violence would prevent His eventual sacrifice. Is this so? What about nothing happening outside of God's will?
There is an interesting passage which shows the key fulfillment of a prophecy pointing to this mystery; partially fulfilled when Peter used his sword. The absence of violence in the Gospel and letters, other than Peter's volition (based on human logic), is evidence to the complete fulfillment.
Believers were massacred, persecuted, thrown into prison and challenged with death when failing to deny Christ as Lord. There is no secular historical evidence showing the believers acted out with violence. No evidence of defending their life or property. None. They faithfully met their death, and as we believe, passage into glory.
When the Roman state adopted the faith as a new religion is when we see the beginnings of carnal defense and justification of violence behind religion. The justifications for the ways of this world are shown, not so much faith in God and His sovereign protection over life.
This departure could arguably insinuate that as the Way absorbed the kingdom(s) of the world, so did it also absorb the ways of men and their natural order. Yet, where is the justification for taking a life other than in the writings of men centuries after Perfection revealed Peace? Is killing allowed by God under the covenant of loving your enemy?