21 The LORD said to Moses, “When you go back to Egypt see that you perform before Pharaoh all the wonders which I have put in your power; but I will harden his heart so that he will not let the people go. 22 “Then you shall say to Pharaoh, `Thus says the LORD, “Israel is My son, My firstborn. 23 “So I said to you, `Let My son go that he may serve Me’; but you have refused to let him go. Behold, I will kill your son, your firstborn.”‘”
24 Now it came about at the lodging place on the way that the LORD met him and sought to put him to death. 25Then Zipporah took a flint and cut off her son’s foreskin and threw it at Moses’ feet, and she said, “You are indeed a bridegroom of blood to me.” 26 So He let him alone. At that time she said, “You are a bridegroom of blood”–because of the circumcision.
27 Now the LORD said to Aaron, “Go to meet Moses in the wilderness.” So he went and met him at the mountain of God and kissed him. 28 Moses told Aaron all the words of the LORD with which He had sent him, and all the signs that He had commanded him to do. 29 Then Moses and Aaron went and assembled all the elders of the sons of Israel; 30 and Aaron spoke all the words which the LORD had spoken to Moses. He then performed the signs in the sight of the people. 31 So the people believed; and when they heard that the LORD was concerned about the sons of Israel and that He had seen their affliction, then they bowed low and worshiped.
There apparently had been some compromise, because Zipporah didn’t want her son to be circumcised. So Moses had compromised, and allowed the boy to remain uncircumcised. God isn’t a big fan of compromise. Ever. In this case, He was going to kill Moses because he had compromised on the symbol of being one of God’s chosen people. Don’t compromise what makes you unique, especially that which makes you unique as a Christian.