Ex 9:12,30 11:1,5, 12:12-13, Jn 14:6
The Egyptians did not recognize the God of Israel as the true God until the people of Israel left Egypt through the blood of the Lamb. (Ex 9:12,30)
Ex 9:12 And the Lord hardened the heart of Pharaoh, and he hearkened not unto them; as the Lord had spoken unto Moses. 30 But as for thee and thy servants, I know that ye will not yet fear the Lord God.
God promised to bring the Israelites out of Egypt through the blood of the Lamb. (Ex 11:1,5, Ex 12:12-13)
Ex 11:1 And the Lord said unto Moses, Yet will I bring one plague more upon Pharaoh, and upon Egypt; afterwards he will let you go hence: when he shall let you go, he shall surely thrust you out hence altogether. 5 And all the firstborn in the land of Egypt shall die, from the first born of Pharaoh that sitteth upon his throne, even unto the firstborn of the maidservant that is behind the mill; and all the firstborn of beasts.
Ex 12:12 For I will pass through the land of Egypt this night, and will smite all the firstborn in the land of Egypt, both man and beast; and against all the gods of Egypt I will execute judgment: I am the Lord. 13 And the blood shall be to you for a token upon the houses where ye are: and when I see the blood, I will pass over you, and the plague shall not be upon you to destroy you, when I smite the land of Egypt.
The Egyptians knew that the God of Israel was the true God only after the Israelites had left Egypt through the blood of the Lamb. (Ex 7:5)
Ex 7:5 And the Egyptians shall know that I am the Lord, when I stretch forth mine hand upon Egypt, and bring out the children of Israel from among them.
Jesus is the only way to meet God. (John 14:6)
John 14:6 Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me.