When I was at seminary, our professor said to the class, "There are some places in the Bible where the text isn't clear law or clear gospel. So you shouldn't preach on them. There are always people in church who are on edge, barely holding onto faith. You'll end up scaring them away. For example, if you don't want to terrify your congregation, never, ever preach on Exodus 4:24-26!"
The text is primal in its simplicity:
“At a lodging place on the way the Lord met him and sought to put him to death. Then Zipporah took a flint and cut off her son's foreskin and touched Moses' feet with it and said, “Surely you are a bridegroom of blood to me!” So he let him alone. It was then that she said, “A bridegroom of blood,” because of the circumcision.”
As they made their way to Egypt, God met them. The Lord struck Moses with a fatal illness. But, Zipporah, who quickly grasps the cause, moves to save her husband's life. She circumcises their son and throws the foreskin at Moses' feet (which is a Hebraism for genitals). Zipporah threw their son's foreskin on Moses’ genitals treating it symbolically as Moses’ foreskin to remind God of his promise. As a consequence, God repents of his anger and allows Moses to recover his health and continue to Egypt.
Zipporah and Moses were bound by blood. More than that, God and Moses were bound by blood. The blood of the circumcision was a sign of God's promise to his people. It was a sign of God's promise to Abraham. It was a sign for the Sons of Israel. One which they would soon paint onto their doorposts on the eve of the Exodus. It was a sign that pointed to the true Bridegroom of Blood who was to come, who would liberate the whole world from sin, death, and damnation.
Zipporah and Moses were bound by blood. More than that, God and Moses were bound by blood.
Jesus' blood sealed the promise given to Moses and Israel. On the cross, the blood of the Bridegroom fulfilled God's one-way covenant with Abraham. Jesus' blood was enough. No more circumcisions. No more beasts sacrificed on Israelite altars. The true Bridegroom's blood was enough. Now, the way is open for everyone to say about Jesus, "You are truly a bridegroom of blood to me." We just need to be washed in the blood of the Lamb.
When we are baptized in Christ's name, we are washed in the blood of the Lamb. The waters of baptism are our sign, not the blood of foreskins. Through water and blood, the whole world was redeemed from sin. Through Jesus' blood and the waters of baptism forgiveness, new life, and eternal salvation are given to us.
In baptism, God's relents of his judgment and promises to be for us in the way of grace and forgiveness, as he's revealed himself to us in Jesus. God's word of promise and the blood is what saves sinners. Moses and Zipporah believed this, and so do we today.
But, in the revelation of who Jesus is for us, the text opens up with a word of law and gospel.
Our professor warned us away from Exodus 4:24-26 because he was looking for a logical reason for what God did to Moses. Outside of Christ Jesus, there's not much logic to what God does to us. Likewise, taken at face value, the verses don't offer comfort to troubled consciences.
But, in the revelation of who Jesus is for us, the text opens up with a word of law and gospel. God comes to kill Moses. Zipporah circumcises her son, throws the foreskin on Moses' genitals treating it as a symbol for Moses' own foreskin, just as Jesus places himself between us and God's furious anger toward sin. The Son holds up his hands, points to his side, and says, "Father, remember your promise." And just like he did for Moses and Zipporah, so the Father does for us because Jesus is truly a Bridegroom of Blood to us!