This is the beginning of the covenant God made with Abraham and that Paul wrote of in Galatians 3. The entire chapter of Genesis 15 is of a special covenant containing promises that God made with Abraham to provide him with an heir and descendants from his own house, and inheritance of the land.
One of the interesting things, at least to me anyway, is to note God's foresight in all of this. Remember, this was before Abraham had any heir at all. We are talking about when he was somewhere shortly after the age of 75 and before Isaac was born. That is a long time before the children of Israel came out of Egypt. God's foresight included some form of discipline for Abraham's descendants that was going to last for 400 years—before the beginning of fulfillment of at least part of what God had in mind here.
You will notice a difference between the 430 years mentioned in Exodus 12 and the 430 years mentioned in Galatians 3, and the 400 years that is mentioned here. Now nobody—and I mean nobody—has been able to know exactly what event began the 400 years, because nobody has zeroed in on an event and it is not written in the Bible, as far as we know.
Researchers have come to the conclusion that the 400 years is simply intended to be an approximation of the 430 years. They back this up with the mention of the four generations in verse 16. Those generations appear to be Levi, Kohath, Amram, and Moses. Since those people lived a great deal longer than we do, the researchers say that God assigned roughly approximately 100 years to each generation. By this, Abraham, in faith, would understand that at some time in that fourth generation would come the beginning of the fulfillment of this prophecy that God made.
We need to understand so we get a bigger grasp on things here because this covenant is awesome. We need to understand that God is inaugurating a much, much larger plan, beginning with Abraham and then continuing through Isaac, who was a type of the Promised Seed, then Jacob and his twelve children (thirteen counting Dinah), Joseph and going down into Egypt, the famine that began while Joseph was there forcing Jacob to go down into Egypt where Israel grew into millions of people, and out of that millions of people God raised up Moses through whom would come the freeing of Israel from their captivity.
Brethren, that was just the first step of the fulfillment of the promises that are contained in this covenant God made with Abraham.
The events of Genesis 15 are a very significant starting point. The events of Exodus 12 and 13 carry those events to its first major, major fulfillment. I said "major, major," because when Isaac was born, that was the first step in the fulfillment of these promises.
The events of Genesis 12 and 13 are the next major step in the fulfillment of this covenant that God is making with Abraham in Genesis 15. What is happening here is that God is, with Abraham and this covenant, formally beginning His spiritual purpose. However, that will be preceded by forming Abraham's physical descendants into a physical nation which God will use for His purposes, and from whom God will draw the bulk of those who are going to be in the first resurrection. We can see it is beginning to step out and include us.
The real beginnings of the Old Testament Church were not at Sinai, but in the land of inheritance where Abraham pitched his tent. Eventually what Stephen gets around to is the New Testament Church, but on his way there he has to establish what he calls "the congregation in the wilderness." So where does the establishment of "the Church in the wilderness" begin? He goes back to Abraham, not to Mount Sinai. That is the foundation. The foundation of God's spiritual purpose is the covenant with Abraham, not what happened at Sinai or anytime after that. The real formal beginning (if we can put it that way) was that seemingly simple ceremony we see in Genesis 15.
From that small … . . .
I do not think we need to read any further. That is far enough there. So God made a covenant with Abram, and I want you to notice two things here. In verse 12, "And when the sun was going down. . ." And then verse 17, " And it came to pass, that, when the sun went down, and it was dark, behold a smoking furnace, and a burning lamp. . ."
Brethren, when did Israel leave Egypt? They went out of Egypt when the sun went down! Exactly 430 years to the day after the covenant was made! We were discussing this yesterday and Richard said that knowing God, they probably went out of Egypt right at the very second to 430 years. We will be conservative and say it was right to the minute. I do not know.
Nobody holds God back from what He wants to do. He says in Isaiah, "My counsel shall stand." This is why the prophecies ring with such a positive assurance. No puny man or angel, or mighty army of angels, or all the nations of men can stop Him from acting on what He purposes to do. Really brethren, under the best of circumstances, we are saved in spite of ourselves anyway.