Various Interpretations
The details of the passage are unclear and subject to debate. One problem is that the text uses pronouns multiple times, without ever identifying which of the three individuals of Moses, Yahweh (the LORD), and Moses and Zipporah's son, is being referred to by each instance. In particular, it is unclear whose feet, Yahweh's, Moses' or her son's, Zipporah touches with the foreskin, and the meaning of "bloody bridegroom".
Because of these difficulties, many biblical scholars consider the passage fragmentary. The ambiguous or fragmentary nature of the verses leave much room for extrapolation, and rabbinical scholarship has provided a number of explanations. Specifically, the Targum Neophyti, a midrashic translation of the Pentateuch into Aramaic, expands Zipporah's enigmatic "you are truly a bridegroom of blood" to "How beloved is the blood that has delivered this bridegroom from the hand of the Angel of Death."
While the passage is frequently interpreted as referring to Gershom, Moses' firstborn, being circumcised, the Midrash actually states that the passage was, at that time, considered instead to refer to Eliezer, Moses' other son. The question on why Moses neglected to have his son circumcised and thus incurred the wrath of Yahweh was debated in classical Jewish scholarship. Rabbi El'azar ha-Moda'i said that Jethro had placed an additional condition on the marriage between his daughter and Moses - that the firstborn son of Jethro would be given over to idolatry and thus explaining why Moses was viewed negatively by Yahweh. One Midrashic interpretation is that, while Yahweh allowed Moses to put off circumcising his son until they reached Egypt, rather than weaken him before the journey, Moses did not hasten to perform the task as soon as possible after he had arrived.
Rabbinical commentators have asked how Zipporah knew that the act of circumcising her son would save her husband. A common explanation is that the angel of God (or one of two angels, Af and Hemah, the personifications of anger and fury), in the shape of a serpent, had swallowed up Moses up to but not including his genitals. Zipporah immediately understood that the threat was related to circumcision, by a "psychoanalytic link" between Moses' penis and his son's, the ambiguous use of pronouns taken by Haberman (2003) as indicating the fundamental identity of the deity, her husband and her son in the woman's subconscious.
Hyam Maccoby, in The Sacred Executioner, interprets the passage as meaning that when God met Moses he (Moses) tried to kill him (Moses' son). On this view the story is an aetiological myth about the origin of circumcision as a substitute for human sacrifice.
Kugel (1998) suggests that the point of the episode is the explanation of the expression "bridegroom of blood" חתן דמ, apparently current in biblical times. The story would seem to illustrate that the phrase does not imply that a bridegroom should or may be circumcised at the time of his marriage, but that Moses by being bloodied by the foreskin of his son became a "bridegroom of blood" to Zipporah. The story has also been interpreted as emphasizing the point that the circumcision must be performed exactly at the prescribed time, as a delay was not granted even to Moses.
Read more about this topic: Zipporah At The Inn