Why did God want to kill Moses before the Exodus?

"And it came to pass by the way in the inn, that the LORD met him, and sought to kill him. Then Zipporah took a sharp stone, and cut off the foreskin of her son, and cast [it] at his feet, and said, Surely a bloody husband [art] thou to me. So he let him go: then she said, A bloody husband [thou art], because of the circumcision. " (Exodus 4:18-26)

Because only one of Moses' sons is mentioned here – not having been circumcised, we must assume the other was! This could have been the cause – could it be that Moses did circumcise his firstborn according to the command of God, and Zipporah (not being an Israelite) – was appalled at the bloody act? And in-turn gave Moses such a hard time over it that he didn't want to go through it again? God knew about the situation and was long suffering in waiting on Moses' to repent. Moses may had hoped God would shut His eyes to the situation and not even bring the matter up.

Why did God purpose to kill Moses? Let us read what the scriptures have to say about circumcision:

" And ye shall circumcise the flesh of your foreskin; and it shall be a token of the covenant betwixt me and you. And he that is eight days old shall be circumcised among you, every man child in your generations, he that is born in the house, or bought with money of any stranger, which is not of thy seed. He that is born in thy house, and he that is bought with thy money, must needs be circumcised: and my covenant shall be in your flesh for an everlasting covenant. And the uncircumcised man child whose flesh of his foreskin is not circumcised, that soul shall be cut off from his people; he hath broken my covenant. " (Genesis 17:11-14)

Not only was Moses head of his household, but God had picked him to be head of the whole nation of Israel – Moses was now going to make a decision – circumcise the boy – or die! Zipporah and Moses must have discussed the matter and she knew Moses was dying before her eyes, making her quick to circumcise the boy! But she was still upset over having to circumcise her son.

"So he [God] let him go: then she said, A bloody husband thou art, because of the circumcision." (Exodus 4:26)

There is more that is not recorded that took place, but is alluded to in Exodus 18: 2-4 :

"Then Jethro, Moses' father in law, took Zipporah, Moses' wife, after he had sent her back, And her two sons; of which the name of the one was Gershom; for he said, I have been an alien in a strange land: And the name of the other was Eliezer; for the God of my father, said he, was mine help, and delivered me from the sword of Pharaoh:" (Exodus 18:2-4)

Why had Moses sent his wife and his sons back? More speculation here – because Moses' son was most likely a young boy, not a baby or small child, circumcision would have made him unable to travel without great pain. And because Moses did not have much to say on this matter here in the scriptures, he would have been embarrassed to have to explain the circumcision of young boy – that is also his son. This would have put him in a bad light before all the people of Israel. Moses may not have wanted to air his sin before the people. But I think it most likely the effects of being circumcised that caused Moses to send his family back to his father-in-law's house. For us to get some idea of the condition of a grown man or young boy we need to look elsewhere in the scriptures for the answer.

" And unto Hamor and unto Shechem his son hearkened all that went out of the gate of his city; and every male was circumcised, all that went out of the gate of his city. And it came to pass on the third day, when they were sore, that two of the sons of Jacob, Simeon and Levi, Dinah's brethren, took each man his sword, and came upon the city boldly, and slew all the males. And they slew Hamor and Shechem his son with the edge of the sword, and took Dinah out of Shechem's house, and went out." (Genesis 34:24-26)

The men of these people were so sick from circumcision that could not defend themselves and were all killed by two men! So Moses' wife needed to stay at the Inn with the boy until he was able to travel – influencing Moses decision to send his family back to Jethro's house. Discerning the scriptures and how Zipporah was a woman who spoke her mind – and most likely not have let up on Moses all the while they were in Egypt – if he hadn't sent her back.

Let's one last time note Exodus 4:25:

"Zipporah took a sharp stone, and cut off the foreskin of her son, and cast it at his feet, [cast it the original Hebrew means "made it touch"] and said, Surely a bloody husband art thou to me."

Zipporah took the foreskin of the circumcised boy and threw it at the feet of Moses along with mouthing her disgust with doing it! There is no more mention of Zipporah after Exodus18 and Moses' sons are not mentioned with any degree of importance anywhere else in the scriptures.