I think Christians thinking they can war at all is bothersome. Jesus said love your enemies and pray for those who persecute you.
I think you are absolutely right. We are to pray for our enemies--and not just to see them cursed and die. Ro 12:17-21, with its call for love towards enemies is clear at least as far as I read. If we are to go into the world and make diciples of all nations we must pray for those who are not saved and, in some cases, are hostile to us. That is a responsibility given to all believers in accordance with the role God gives--plant, water, harvest. God does allow for self-defense at least it is implied in Luke 22:36 Jesus said to them, "But now if you have a purse, take it, and also a bag; and if you don't have a sword, sell your cloak and buy one. ." If you are killed before you share the gospel to a non-believer there is not much spreading of the gospel. But these are personal madates.
I also see scripture as saying the State is ordained and lifted up by God (Romans 13:1). There are civil mandates apart from personal mandates that govern individual action. The State has an obligation to keep order Romans 13:4-6 4 For he (civil authority) is God's servant for your good. But
if you do wrong, [you should dread him and] be afraid, for he does not bear and wear the sword for nothing. He is God's servant to execute His wrath (punishment, vengeance) on the wrongdoer. 5 Therefore one must be subject, not only to avoid God's wrath and escape punishment, but also as a matter of principle and for the sake of conscience. 6 For this same reason you pay taxes, for [the civil authorities] are official servants under God, devoting themselves to attending to this very service.
To me this justifies police and the military as, in Roman times, the police force was the military. Annecdotally Christ did not condemn the centurion in Matt 8:6-13. Jesus actually praised the centurions faith and did not mention the need for the centurion to go sin no more as Jesus did at other time
Matt 8: 6-13 6"Lord," he said, "my servant lies at home paralyzed and in terrible suffering." 7Jesus said to him, "I will go and heal him." 8 The centurion replied, "Lord, I do not deserve to have you come under my roof. But just say the word, and my servant will be healed. 9 For I myself am a man under authority, with soldiers under me. I tell this one, 'Go,' and he goes; and that one, 'Come,' and he comes. I say to my servant, 'Do this,' and he does it." 10 When Jesus heard this, he was astonished and said to those following him, "I tell you the truth, I have not found anyone in Israel with such great faith. 11 I say to you that many will come from the east and the west, and will take their places at the feast with Abraham, Isaac and Jacob in the kingdom of heaven. 12 But the subjects of the kingdom will be thrown outside, into the darkness, where there will be weeping and gnashing of teeth." 13Then Jesus said to the centurion, "Go! It will be done just as you believed it would." And his servant was healed at that very hour.
The separate responsibility of the state verses the responsibility of the individual has profound implications for how a nation defends itself. Had the crusades been organized as a state function and not as a theocratic edict I would be more comfortable with what took place. If that was the case Byzantium would not have been invaded by the crusaders. As it was the Church mandated it (The German King was excomminicated for not taking part in a crusade or supporting one) and special dispensation was given to kill in the name of Jesus. Then to add insult to injury, several of the crusaders like the Normans used the situation to expand their own economic power.