Not so with my servant Moses. He is faithful in all my house. With him I speak mouth to mouth, clearly, and not in riddles, and he beholds the form of the LORD. Why then were you not afraid to speak against my servant Moses?
Jealous of their brother’s leadership and evidently prejudiced against Moses’ gentile wife, Miriam and Aaron turn against him and unwittingly turn against God in their complaints. At issue is the spiritual leadership that God gave to Moses. Miriam had prophesied after the Red Sea crossing (see Exodus 15:20) and Aaron served as High Priest. Their challenge to Moses assumes that they were spiritually his equal and better qualified to lead Israel then their “gentile-loving” brother.
The pretense for their claim to authority is an incipient bit of racism. They speak against the “Cushite” wife of Moses. Elsewhere she is said to be Midianite. Some old commentators among the rabbis suggest that Midia and Cush shared a porous border, potentially making Zipporah’s ancestry Ethiopian, perhaps even black African. Perhaps because of emerging Jewish identity through the new commitment to the Law at Sinai, Moses’ family resented these close gentile connections in their brother. God certainly had not said anything bad about this, in fact, Moses was already married to a gentile when God chose him to be the leader of the Exodus generation. It was the evil hearts of Aaron and Miriam that did not like the situation.
God quickly defended Moses as leader and as clearly His choice for the job. Miriam was struck with advanced leprosy, making her truly unclean, worse than the “gentile” she despised. Gentiles could enter the outer courts of the tabernacle. Lepers could not. The punishment fell upon her 1) perhaps because she led the complaining and accusations in the revolt, and 2) because Aaron was the High Priest, God sovereignly and mercifully spared the nation the trauma of an unclean priest forcing the appointment of a new High Priest.
Moses meekly let God be His defense. By pleading for Miriam’s healing, he proved to his family and a watching nation that his closeness to God’s heart was the strength of his leadership. Miriam was healed after a week-long exile from the camp. Aaron was spared by God’s mercy. And God used the incident to strengthen the leadership of Moses among an increasingly difficult nation.