The New Testament is quite different, of course. Jesus did not lead an army in a rebellion, but rather willingly handed himself over to be crucified. "My kingdom is not from this world. If my kingdom were from this world, my followers would be fighting to keep me from being handed over to the Jews. But as it is, my kingdom is not from here." (John 18:36)
War imagery reappears mainly in Revelation, where Jesus is depicted as having a sword coming out of his mouth, destroying Satan, and judging the nations. There are of course many references to judgment throughout the New Testament, but rarely are there explicit images of weapons and violence.
It seems there are many formulas for how to tie all this together. Some say that God is a God of wrath, and that both the Old Testament calls to holy war and the war imagery of Revelation are both consistent with his character. Rather than fret over these images, we need to respect them, fear God, and teach that his terrible wrath is a reality people will have to face unless they repent.
Rather than try to thoroughly critique this position, I will just state briefly why I have problems with it. To be clear, the main difficulty is not that God judges. It is rather the explicit commands in the Old Testament to (for example) kill women and children.
When you draw near to a town to fight against it, offer it terms of peace. If it accepts your terms of peace and surrenders to you, then all the people in it shall serve you at forced labor. If it does not submit to you peacefully, but makes war against you, then you shall besiege it; and when the Lord your God gives it into your hand, you shall put all its males to the sword. You may, however, take as your booty the women, the children, livestock, and everything else in the town, all its spoil. You may enjoy the spoil of your enemies, which the Lord your God has given you. Thus you shall treat all the towns that are very far from you, which are not towns of the nations here. But as for the towns of these peoples that the Lord your God is giving you as an inheritance, you must not let anything that breathes remain alive. You shall annihilate them--the Hittites and the Amorites, the Canaanites and the Perizzites, the Hivites and the Jebusite--just as the Lord your God has commanded, so that they may not teach you to do all the abhorrent things that they do for their gods, and you thus sin against the Lord your God. (Deut. 20:10-18, emphasis mine)When I take this passage literally, I simply don't know how to square it with the ethical teaching of Jesus to love your enemies and pray for those who persecute you. And I don't know why Jesus would have suddenly changed the strategy from war to self-sacrifice. We could argue about details all day long, but ultimately I just don't see how to form a coherent view of Scripture out of a literal reading of the Old Testament.
There is another way of reading the Bible which seems to be embedded in everything Jesus himself says. It is a spiritual allegory, a prophecy about him and his ministry, and about the ultimate destiny of those who follow his Way.
Jesus does indeed perform acts of war in the New Testament--against demons!
If Satan casts out Satan, he is divided against himself; how then will his kingdom stand? If I cast out demons by Beelzebul, by whom do your own exorcists cast them out? Therefore they will be your judges. But if it is by the Spirit of God that I cast out demons, then the kingdom of God has come to you. Or how can one enter the house of a strong man and plunder his property, without first tying up the strong man? Then indeed the house can be plundered. (Matthew 12:26-29)But spiritual warfare is not physical warfare, and Jesus did not come to lead an armed rebellion against the Romans. How then might we read the Old Testament (and Revelation) in light of his ministry and his character?
I read it spiritually in this way. The people of Israel is the human spirit. Once we were slaves in Egypt. This is a metaphor for our slavery to sin and death. Then God called us out of Egypt with might acts of power, and he gave us a new identity. He gave us his law, so that we might be united. But as everyone who has ever put faith in God knows, it is easy to stumble, right from the very beginning. Even after we are made free in God, we must then wander through the wilderness, just as the Israelites did for forty years.
The final mission is to go into the promised land and conquer. If in the beginning God did all the acts of power himself, liberating us by his own hand, so that we had only to stand back and watch, in the last act we must take up arms ourselves--against the demons of our own hearts. We must utterly annihilate them, wiping out even women and children, which means metaphorically that we must destroy even the possibility of our sins being reborn, thus coming back to haunt us ("so that they may not teach you to do all the abhorrent things that they do for their gods"). It is still God who fights for us, but his power is infused into our own efforts.
But why should the word of God come to us as such a long history when it would have sufficed to simply teach us this brief lesson? Well, I don't agree that it would have sufficed. First of all, we should not discount the fact that the Bible's historical books do indeed record events of history, even if it they are presented in a spiritual (and often mysterious) way. There is always value in such records.
Second, there is no end to all of the subtle lessons one can learn by meditating on the details of sacred history. For instance, I am quite fond of the story of the Gibeonites in the book of Joshua. Since they fear defeat by the Israelites, the Gibeonites dress themselves up in rags and pretend to come to the Israelites from a long distance. The Israelites make peace with them before consulting the Lord, and so they disobey God. In the same way, our sins often dress up to us as outsiders; we think that such faults could never come from our own hearts, but must somehow be the influence of our environment. Or they dress up as outsiders, in the sense that they are not a threat to us, and so we make an alliance with them and permit them to go on dwelling in our souls. "Show no pity," God says. If we do not consult him, our sins will remain, and we will not live long in the promised land (that is, spiritual life) as he desires for us.
That is how I read the Bible these days. It is not that I totally discount the literal meaning of texts--indeed, I take the story of Jesus's death and resurrection quite literally. And I don't think my lens of interpretation is out of line with traditional Christian reading. But at some point, I simply can't accept that all of the words of Scripture are literally true, in the sense that the God of the universe would actually order women and children to be killed (or, alternatively, taken as property). My conviction is that Jesus himself teaches us a new way to fight our wars, one that is spiritual and not literal. This does not require less strength, but more.