The is so much mystery wrapped up in the Exodus, none weirder than the near death of Moses before his wife touches his feet with his son's foreskin! What's up with that?! Let's start by looking just before that section.
"22Then say to Pharaoh, ‘This is what the LORD says: Israel is my firstborn son,a 23and I told you, “Let my son go,a so he may worshipb me.” But you refused to let him go; so I will kill your firstborn son.'"
God's plan from the beginning was to kill the firstborn son of pharaoh! What a picture of the gospel! For His chosen people to be set free it will take the death of the firstborn son!
Now back to the super weird verse about circumcision. The sign of the covenant God made with Abraham was circumcision, with this covenant Abe would be blessed with innumerable offspring, have a relationship with God and be given a land of his own. A land that is to be holy, set apart for God's people. So much so that later on when Moses strikes a rock instead of speaking to it, he is not allowed to enter. God will even allow a generation of faithless Hebrews to die before giving the land to their offspring. Enter Moses on his way to this promised land, he may be God's chosen person to lead Israel out of Egypt, but God still expected him to be obedient in all areas of faith and practice. And according to Gods covenant with Abraham, Moses' son should have been circumsized.
Other random observations:
Exodus 5:2- Pharaoh- 'who is The Lord?'- demonstrates Pharaoh doesn't know God.
Exodus 5:20,21- Obedience is met with hardship. Israelites first reaction is to blame God. This becomes a pattern...
Exodus 6:2-5- this one is really interesting, God reinforces his name not Elohim, but Jehovah. He gives a fuller revelation to Moses than the patriarchs.
Exodus 6:15- one of the ancestors of Moses was the son of a Canaanite woman.
Exodus 7:5- The signs were so the Egyptians would know God.
Exodus 7:10-13- The magicians staffs also become snakes but Moses snake eats them.