“Let him who desires peace, prepare for war.” – Vegetius
One interesting argument for the justification specifically of serving in the military is to point out that Paul uses military imagery all over his writings (2 Cor 6:7; 2 Cor 10:3-51; Thess 5:8; Phil 2:25; Philemon 2; Rom 16:7; Eph 6). Now, could you ever imagine the Bible describing Christians using metaphors of sinful activities? Of course not! Perish the thought!
It makes sense to me that if the Bible uses a metaphor, such as soldiers, or athletes, or farmers, or sheep, then such things are probably not an abomination!
However, Christians like to point to Christ and say, “Look at how peaceful He was, and how much He commanded us to refrain from violence!”
Ah yes, but once again, Christians are failing to look at all sides of the issue. In Luke 22:36-38, Christ commands his disciples to buy swords for themselves. Many Christians spout that this command was either entirely figurative, or it was for the purpose of later teaching a lesson of peace and non-violence. Neither interpretation is acceptable in my opinion, nor does it bear intellectual or exegetical integrity.
If one reads the passage honestly and in a practical reading, Christ appears to command the purchase of swords for physical protection due to the fact that they would be considered outlaws, just like the prophecy stated in Isaiah 53. People often then say “What about the passage where Christ rebukes Peter for drawing his sword and defending Christ in the garden when He was about to be arrested?” But most people do not even pay attention to the reason Christ Himself gave for this rebuke. In John 18:11 we see Christ’s reason for rebuking Peter, “Sheathe your sword! Am I not to drink the cup which the Father has given Me?”
Just because Christ chastised Peter for interfering with His arrest, jeopardizing the salvation of the entire human race, by the way, doesn’t mean that Christ was some spindly little code pink pacifist! No, that was the same Christ who armed Himself with a whip and smashed and fought His way through the temple when He saw people were using it as a marketplace (Matt. 21).
Christ knew when it was a time for peace, and when it was a time for war (Eccl. 3:8).
Instead of just saying violence is always wrong, just because it’s easier to make universal calls like that, we should strive to have the same kind of discernment Christ had.