I am considering a job offer from a company whose parent company is involved in the weapons industry. This obviously raised some questions for me as a Christian. On the one hand, Jesus' teaching and lifestyle were in general pacifistic (e.g. Matt 5:38-48 -- which includes prohibition of killing). On the other hand, Peter and Paul identify official authority as instituted by God to protect "good" and punish "evil" (Rom 13:3-4; 1 Pet 2:13-14). Further, Jesus allows his disciples to bear and even to use the sword (Luke 22:36; John 18:10), at least for self defense (Luke 22:36; John 18:10). He also cleansed the temple of traders and animals by means of a whip (John 2:15). So my provisional conclusion: God teaches me to be a total pacifist on a relationship level (social life), but on the state level He allows me the use of power to protect the innocent and to combat evil. What do you say?

[Edited and posted with permission]

Whether the Lord deals with us on two levels remains to be demonstrated, yet overall I agree: you are right to think hard before making your decision. In my opinion, we need to keep our distance from weapons manufacturing. If my professional contributions were directly financing warfare, I'd resign. (I'm not normally a squeamish or particularly sentimental person, but I cannot imagine Jesus creating mines, chemical weapons, bioweapons, or nuclear devices to be used against my brothers and sisters -- let alone on those who are not ready to meet the Lord.) But if they weren’t directly supporting war, I would probably try to remain. Further thoughts:

  • Peter and Paul identify official authority as instituted by God to protect good and punish evil, yet this has nothing to do with whether Christians may resort to violence. Peter and Paul are referring to the government. (There is no such thing as a Christian government, since governments rely on coercion, and disciples of Christ are not allowed to coerce anyone -- even their enemies.)
  • As for bearing the sword for self-defense, Jesus rebuked Peter for drawing the sword, even when Peter was attempting to protect an innocent person (Jesus)! Further, if he was advocating bearing arms, two swords would be way too few for the Twelve! 
    • A likely reason Jesus told the disciples to get swords was so that they would become the “transgressors” among whom he would be counted, and thus fulfill Scripture (Luke 22:36-38). Jesus was not happy when Peter used the sword.
    • Or he may have beensaying something like “From now on, you will be in danger.” When his disciples took him literally, he said “Enough!” (They did often misunderstand the Lord when they took him literally, didn't they?) 
  • Jesus did cleanse the temple by means of a whip, yet there's no indication he attacked people. Nor that he hurt anyone. This was not a Roman cat-o'-nine tails (used for scourging). The text in John 2:15 indicates that the whip was readied for sheep and cattle only. Jesus' action of wielding the whip may have scared the humans away, however.
  • God could be teaching pacifism on a relationship level (social life), yet not on an official or state level, only if the teaching of Martin Luther is correct. He taught that each Christian is really two persons, one standing before God as a follower of Christ's commands, the other a representative of the state, who is not required to follow Jesus' teaching in Matt 5 and elsewhere. But biblically we are only one person. If the government tells you to assassinate someone, or to sleep with a double-agents’s wife in order to extract state secrets, or torture its enemies, you must refuse — as did the early church (unanimously) until the 4th century.
  • There is a secondary problem with Christians fighting: "Which side to fight on?” God has supported “righteous” nations against the “unrighteous” (Israel against Canaan), just as he has supported the “wicked” against the “less wicked” (Babylon against Israel). Since God has given no modern nation a covenant commitment to fight a holy war, we would end up with disciples slaying disciples -- on both sides!
  • The church's position on military service was simple: No idolatry, no oaths (like swearing to the genius of Caesar), and no killing. Otherwise one had to resign—even if it meant execution.
  • National service may not be required in the U.S., but as you know it is required in many nations. As long as one can serve without sinning (immorality, profanity, killing, drunkenness…) there is no biblical problem. Along these lines, someone already serving in the military, or as a police officer, or other armed profession, need not resign as long as he / she is determined to obey God. This also explains, I think, why a fellow like Cornelius wasn’t told to resign when he heard the gospel (Acts 10). I think it doubtful he was killing, or in charge off killing, at the time Peter met him. The Roman army did occasionally fight, but during the Pax Romana (which includes the 1st and 2nd centuries) it was more a peacekeeping (police) force, whose primary duties included building roads.
  • It is clear from church history when the church sanctioned violence. The change began with Constantine (d.337) — violence among church people steadily increasing until Augustine and Ambrose formulated “Just War Theory” to legitimize violence (which itself implies that military violence was a novelty). God's people under the new covenant had been unanimously pacifist for their first 300 years. It is only in the 4th century that we find Christians permitting killing.
  • Note: Pacifism, working for peace by modeling the behavior of Christ (loving service, reconciliation, prayer, and so forth) should not be confused with passivism, which is selfishly doing nothing.
  • Sadly, the disastrous fourth century saw peaceful disciples turn into persons of violence; the persecuted became the persecutor (!). Within a few generations, Christians were participating in riots, vandalism, lawsuits, killing, and dozens other behaviors that discredited the gospel and dishonored Christ.