CLAIM: Why would God want to kill Moses, if he selected him to lead his people out of slavery?
RESPONSE: While the NIV places Moses’ name in the passage, the Hebrew doesn’t explicitly tell us who was going to be killed. Since the context refers to the firstborn son of Egypt (v.23) and the circumcision of Gershom (v.25), some commentators believe that Gershom –not Moses –was the one being threatened by God. However, this does little to solve the difficulty of this passage!
For whatever reason, Moses had not circumcised his son. The penalty for refusing circumcision was to be “cut off” from the people (Gen. 17:14). Since Moses wouldn’t have carried out this act, God was threatening to do it himself! When God threatened Gershom with death, Zipporah immediately knew what was going on. She must have been arguing with Moses over the circumcision issue for some time. God was probably concerned that a hypocrite would teach his commandments to his people, and God was taking a hard line with him. If God really wanted to kill Gershom, he easily could have. Instead, he threatened death, so that Moses would make a decision about circumcising his son. The point of this passage is to show that a leader’s household needs to be in order before they are ready to serve God (1 Tim. 3:4). This also demonstrates that leaders have higher standards than those not in leadership. Before he was leading, God didn’t bring up this issue with Moses. However, after he stepped forward to lead, this issue became important to God.
 See Stuart, Douglas K. The New American Bible Commentary: Exodus. Vol. 2. Nashville, TN: B & H Group, 2006. 153.