This part of the story sits awkwardly in the text. If someone was inventing a story to tell, this detail would be one left out. But, when recording actual events in narrative form—one cannot escape the awkwardness of the story.
The Lord meets Moses at one of the lodging places on the way to Egypt in order to kill him. The reason is obscure at best in the text. We don’t know God’s method—whether causing Moses to experience such inner turmoil about something or physically meeting Moses as He will Balaam later in the narrative (cf. Numbers 22:21ff). Recognizing that God was in some manner standing against Moses, Zipporah circumcises their son and throws the foreskin at Moses’s feet saying, “You are indeed the bridegroom of blood to me.” At this moment, God stops oppressing Moses. The text is perspicuous. God leaves Moses alone because of the circumcision.
This part of the story, and this part of history, is purposefully placed directly after God rejects the firstborn of Egypt and calls Israel His firstborn son (cf. v. 22). Zipporah and Moses’s son are God’s people, part of His firstborn nation. They are not Egyptians. They are not Midianites in God’s eyes. Here, even before the Law is given, circumcision signifies such citizenship and sonship. It seems as though, in some way, Moses was keeping his son from God. As we see with Jesus in the New Testament, it is better for a person to die if he keeps children from the Lord or causes God’s children to stumble (cf. Matthew 18:6; 19:14).
Now, Christ has come and the gentiles have been included in God’s covenant people (cf. Isaiah 19:23-25; Zechariah 14:16; Ephesians 3:6). Further, Gentiles are not required under Mosaic Law to be circumcised (Acts 15:1ff). God does not change. He is still a covenant God. Parents still have the responsibility under heaven to bring their children into the covenant people of God; that is the highest responsibility of any parent—such that God still opposes men who do not raise their children in His faith. God will never withhold salvation from His chosen people. He will oppose us, and often does when we live foolishly by trying to withhold from God that which is His covenantally. This is why so many gentile believers are so adamant about baptizing their children. While I am not a paedobaptist and do not believe baptism is the new circumcision, I understand the covenant community. So, we cannot fault parents who want to symbolize their children’s entrance into the covenant community by baptism—so long as the baptism is not seen as salvific. It certainly isn’t an issue to argue about—especially when many parents are withholding their children from the Lord and raising them as either practical atheists or agnostics. The church, thus, needs to equip parents and minister to the young. We can read over every page of Scripture and confidently say, “Woe to those who reject or deflect the younger generations. Blessed are those to a thousand generations who love God and keep His commandments” (cf. 20:5-6).