Blessed be the Lord my Rock,
who trains my hands for war, and my fingers for battle my lovingkindness and my fortress, my high tower and my deliverer, my shield and the One in whom I take refuge, who subdues my people under me. (Psalm 144:1)
It is God who arms me with strength, and makes my way perfect. He makes my feet like the feet of deer, and sets me on high places. He teaches my hands to make war, so that my arms can bend a bow of bronze
I have pursued my enemies and overtaken them; neither did I turn back again till they were destroyed. I have wounded them, so that they were not able to rise; they have fallen under my feet.
For You have armed me with strength for the battle; You have subdued under me those who rose up against me. (Psalm 18:32,37)
The Lord is a man of war; the Lord is His name
Your Right Hand, O Lord, has become glorious in power;
Your right hand, O Lord, has dashed the enemy in pieces. And in the greatness of Your excellence you have overthrown those who rose against You; You sent forth Your wrath which consumed them like stubble. (Exodus 15:3,6)
Many Roman soldiers and centurions in the New Testament are praised for their character, and there are no instances in which their career is critisized or they are encouraged to leave their careers as soldiers:
Matthew 8:5-13
When Jesus had entered Capernaum, a centurion came to him, asking for help. 6 Lord, he said, my servant lies at home paralyzed and in terrible suffering.
7 Jesus 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.
13 Then 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.
Luke 7:
7 When Jesus had finished saying all this in the hearing of the people, he entered Capernaum. 2 There a centurions servant, whom his master valued highly, was sick and about to die. 3 The centurion heard of Jesus and sent some elders of the Jews to him, asking him to come and heal his servant. 4 When they came to Jesus, they pleaded earnestly with him, This man deserves to have you do this, 5 because he loves our nation and has built our synagogue. 6 So Jesus went with them.
He was not far from the house when the centurion sent friends to say to him: Lord, dont trouble yourself, for I do not deserve to have you come under my roof. 7 That is why I did not even consider myself worthy to come to you. But say the word, and my servant will be healed. 8 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.
9 When Jesus heard this, he was amazed at him, and turning to the crowd following him, he said, I tell you, I have not found such great faith even in Israel. 10 Then the men who had been sent returned to the house and found the servant well.
Acts 10:
10 At Caesarea there was a man named Cornelius, a centurion in what was known as the Italian Regiment. 2 He and all his family were devout and God-fearing; he gave generously to those in need and prayed to God regularly. 3 One day at about three in the afternoon he had a vision. He distinctly saw an angel of God, who came to him and said, Cornelius!
4 Cornelius stared at him in fear. What is it, Lord? he asked.
The angel answered, Your prayers and gifts to the poor have come up as a memorial offering before God. 5 Now send men to Joppa to bring back a man named Simon who is called Peter. 6 He is staying with Simon the tanner, whose house is by the sea.
7 When the angel who spoke to him had gone, Cornelius called two of his servants and a devout soldier who was one of his attendants. 8 He told them everything that had happened and sent them to Joppa.
Finally - Ephesians 6 - the imagery of a soldier is hard to miss - or dismiss - and is certainly not derogatory.
10 Finally, be strong in the Lord and in his mighty power. 11 Put on the full armor of God so that you can take your stand against the devils schemes. 12 For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. 13 Therefore put on the full armor of God, so that when the day of evil comes, you may be able to stand your ground, and after you have done everything, to stand. 14 Stand firm then, with the belt of truth buckled around your waist, with the breastplate of righteousness in place, 15 and with your feet fitted with the readiness that comes from the gospel of peace. 16 In addition to all this, take up the shield of faith, with which you can extinguish all the flaming arrows of the evil one. 17 Take the helmet of salvation and the sword of the Spirit, which is the word of God. 18 And pray in the Spirit on all occasions with all kinds of prayers and requests. With this in mind, be alert and always keep on praying for all the saints.