I think the answer to your questions, dear TAI (and may you have peace...) is summed up in a couple things, including something my Lord, JAHESHUA MISCHAJAH, the Holy One of Israel and Son and Christ of the Most Holy One of Israel is recorded to have said.
I think I'm going to portray a Bible believin', God-fearin'. true Christian fightin' SOB.
Certainly you know that not all who profess to be Israel... are Israel. And the same applies to "christians." Just because one CLAIMS to be a "christian" (usually because they "like" the teachings of my Lord, but that doesn't necessarily mean they FOLLOW them...)... does not mean one IS a christian. To literally be a christian, one must have been anointed with holy spirit. For that IS what the name means: "chosen/anointed person". Christ (kristos) person. If one has NOT received such spirit, one is merely one of those who "go with" the Household of God... "Israel." But because they have not been grafted INTO the House... they are actually more like the "vast mixed company." And no, that is NOT the "great crowd" - the great crowd are people of EVERY nation, tribe and tongue... who have been grafted into Israel... by means of having washed their robes white... in his blood.
Also, my Lord is recorded to have said, ""Not everyone who says to me, 'Lord, Lord,' will enter the kingdom of heaven, but only he who does the will of my Father who is in heaven. Many will say to me on that day, 'Lord, Lord, did we not prophesy in your name, and in your name drive out demons and perform many miracles?' Then I will tell them plainly, 'I never knew you. Away from me, you evildoers!'
So, simply because people do things in his name... also does not make them a christian. It would be like someone learning the laws of Israel... then going out and slaying people who transgressed the law... then claiming to be Israel because of doing so and because of adhering to the law. Unless such person was CIRCUMCISED, however, they still weren't an Israelite. Applying that to so-called "christians"... unless that person has undergone circumcision (meaning, cutting away the flesh)... of the HEART... which "circumcision" is performed by GOD... through His Son and Holy Spirit, CHRIST... then they aren't "Israel"... and thus, aren't christians.
Paul also had a very revealing comment: "The weapons we fight with are not the weapons of the world. On the contrary, they have divine power to demolish strongholds." 2 Corinthians 10:4
My Lord had the power to call down myriads in his defense, and yet didn't. Can someone say they are following in his footsteps and then go out and instigate war? I am not so sure.
I also want to leave you with this thought: on 911, the WTC was attacked. Many in the US took (and still take) it as a personal offense. In their minds, it was they who were being attacked and so retaliation was and is appropriate. Personally, I saw a system attacked. A system set up by various governments, that of the country I live in and others. And so, I did not take it personally. I understand that the country... and the system of that country... is touted to be one of the best in the world, indeed perhaps the best known to mankind. What many forget, however, is how that system even came to be. IF, however, the very people kidnapped and brutally forced to BUILD that system had revolted... had taken up arms and slaughtered every man, woman, and child who put them under such a heinous institution (and, yes, I am talking about the institution of free labor that build this country and its system - African slavery)... there would BE no system... as we know it now... TO retaliate FOR. Thus, SOMETIMES... pacifism ISN'T such a bad thing.
Personally, I believe I have more to worry about with the riffraff, thieves, and drug addicts that live in my town... than I do of Osama Bin Laden, Al-Qaida, Hamas, Hezbollah, or the Taliban. If, however, I chose to take up arms and go after THESE... I would be considered a "vigilante" and taken to jail.
Military service is not "wrong," for a true christian - again, there are MANY things such one can do in such "service." Murder, however, is wrong... for anyone. And plotting to kill... anyone... is murder. No matter what the "rules" of war says, it is murder because it requires PREMEDITATION. Defending oneself is NOT murder... and the one defending has every right to do so; however, when it comes to one being persecuted for CHRIST... when one is being attacked solely on the basis and for the reason that one IS a "christian"... one has an example to follow. Christ. In order to say one BELONGS to HIM... one must do as he WOULD do. And we have the example of that. We know what he did.
I bid you peace... and the wish that whatever "anger" you possess, against whomever... and whatever vengeance you feel YOU must mete out... is at some point put into its proper context.
YOUR servant and a slave of Christ,
SA