The Book of Exodus operates with an unexpected understanding of holy war.
After the miraculous crossing of the Red Sea, Moses and the Israelites break out into a song of rejoicing (Exodus 15:1-18). It celebrates God’s unexpected deliverance of the people in their time of greatest peril. Its opening verses read:
I will sing to the Lord, for he has triumphed gloriously;
horse and rider he has thrown into the sea.
The Lord is my strength and my might,
and he has become my salvation;
this is my God, and I will praise him,
My father’s God, and I will exalt him.
The Lord is a warrior;
the Lord is his name. (Exodus 15:1-3)
The song is full of martial imagery, using the language of battle to describe the victory over the Egyptians in the sea. This is language that resonates with other ancient Near Eastern mythologies. One of the best known is the Babylonian creation myth, Enuma Elish. In the Babylonian myth, the sky god Marduk goes into battle with the sea goddess Tiamat, goddess of chaos. He defeats her after a ferocious duel and creates the world from her carcass. *

It should not surprise us then to find that Exodus explicitly calls God a warrior. This is the language of holy war. That may make us very uneasy, given our modern experience of hearing the language of holy war used to justify terrorism and indiscriminate attacks on civilian populations. It is easy then to lump the God of the Old Testament in with all those other blood-thirsty gods of history.
If we do so, however, we may miss a shift that has gone on in this song. As I said, God is described as a warrior. But God fights not for his own aggrandizement, but for the liberation of his people. He is a warrior on behalf of his people.
The usual way that we talk about holy war is of people fighting on behalf of God’s cause. We fight to glorify God, promote his worship, and advance his cause in the world.
That is the way the crusaders thought about their expeditions to regain and protect the Holy Land. It is likewise the way Muslim jihadists think about their attacks. They believe that piety requires them to fight on behalf of Allah’s cause. They go into action in fact with the cry “God is great!”
There is plenty of conflict in the Book of Exodus, but notice it is not the Israelites who go into battle with the Egyptians. Even as reclusive guerrillas, crying “God is great!”, they never attack the Egyptians. All the fighting is done by God, and done on behalf of the cause of Israel’s liberation. The battles in Exodus are a holy war not because the people are doing the fighting on behalf of God, but because God is doing the fighting.
God is motivated in his fight with Pharaoh and the Egyptian army not by hatred for the Egyptians, but by his intense love for the Israelites and his faithfulness to his promises to their ancestors. We hear that said explicitly in Exodus 15:13:
In your steadfast love you led the people whom you redeemed;
you guided them by your strength to your holy abode.
The language of Exodus 15 then does not give God’s people warrant to pick up the sword, the gun, the bomb to advance God’s cause, to glorify God’s name, or to bring unbelievers under God’s reign. When we use the language of holy war, we need to remember that in the biblical context, it is language to describe God’s actions on our behalf–to liberate us from the forces of oppression, bondage, and death that keep humans from flourishing.
Additional Note:
In what I have written about holy war, I do not want you to think that I am ignoring the fact that Exodus 17:8-13 describes a battle between the Israelites and Amalekites. This battle, however, is not initiated by the Israelites. They do not go into battle to advance God’s cause. They go into battle in self-defense after they are attacked by the Amalekites.
Nor am I ignoring the fact that God calls upon the Israelites to revenge themselves on the Midianites who deceive them in Numbers 25. And God calls upon the Israelites to eradicate the Amalekites in 1 Samuel 15. In both cases, God’s motivation is said to be to exercise punishment on two tribes that have harmed and attacked the Israelites. We may feel many qualms about texts that imply God indulges in revenge. But both passages still maintain that understanding that God is the ultimate fighter fighting on behalf of his people.
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* A good translation of the myth is found in Stephanie Dalley (editor and translator), Myths from Mesopotamia: Creation, The Flood, Gilgamesh, and Others. Oxford World Classics, 1989.