The Bible does not say much about Moses’ wife, Zipporah. We know that she was the daughter of a man called Jethro (or Reuel), who was a priest in the land of Midian (Exodus 3:1; cf. 2:18). The Bible does not explicitly say that Moses had more than one wife. However, Numbers 12:1 leads many to surmise another wife: “Miriam and Aaron began to talk against Moses because of his Cushite wife, for he had married a Cushite.” The question of the number of Moses’ wives hinges on the identity of this Cushite (or Ethiopian) woman. Is this a reference to Zipporah? Or is this another woman?
First, some background. While he was still in Egypt, Moses killed an Egyptian guard who was assaulting a Hebrew slave, and he hid the body. Soon, Moses got word that Pharaoh knew what he had done and was going to kill him, so he fled from Egypt to the land of Midian to avoid prosecution. When he got to Midian, he sat down by a well, and there he encountered a family living in that area. The priest of Midian had seven daughters, shepherdesses who came to water their father’s flock. Some shepherds tried to drive the women away, but Moses fought the shepherds off and helped the women, even drawing water for their animals. The seven reported this heroic action to their father, and he asked Moses to come and eat with his family. Sometime later, Moses was married to Zipporah, the daughter of Reuel, the priest of Midian (Exodus 2:16–22).
In later chapters Reuel is called Jethro. There is no explanation for this name change, but the title “priest of Midian” accompanies both names, and he is called Moses’ father-in-law, so it is safe to assume this was the same man. The only other possibility is that there were two priests of Midian, one called Jethro and one called Reuel and that Moses had married a daughter from each family—but that would be very unlikely.
More evidence that Moses only had one wife is found in Exodus 4:20: “Moses took his wife and sons, put them on a donkey and started back to Egypt.” Wife is singular, and there is no mention of any other wife or wives that Moses had. On the way to Egypt, Zipporah circumcised their son and thus saved her husband’s life—Moses had neglected to obey the Lord in this matter, and the Lord would have killed Moses had not Zipporah intervened (Exodus 4:24–26). After this event, it seems that Moses sent Zipporah and his sons back home to stay with Jethro. We don’t encounter Zipporah again until after the exodus when she returns to Moses in the wilderness (Exodus 18).
That brings us to Numbers 12:1 and the reference to Moses’ marriage to the Cushite, or Ethiopian. It is possible, though not probable, that the Cushite is Zipporah. Arguing against that possibility are two facts: 1) the link between Midianites and Ethiopians is very difficult to trace convincingly; and 2) the objection to the marriage raised by Miriam and Aaron seems to indicate a recent event. Moses and Zipporah would have been married for over 40 years by this time, and it is unlikely that Moses’ siblings would just then be protesting. Much more likely is that Zipporah had died (although her death is not recorded in Scripture) and that Moses had remarried.
Some see in Moses’ marriages to two Gentiles as prefiguring the gospel message going into all the world, blessing even the Gentiles (see Acts 1:8). Zipporah the Midianite was related to the Israelites but only through Abraham’s son by a concubine (Genesis 25:1–2); the Cushite was farther removed from the lineage of Israel. Moses’ marriages expanded in a widening circle into the Gentile world, helping to show that in Abraham’s seed all the nations of the world would be blessed (Genesis 12:3).