Paul mentions that Abraham was called by God, at which time certain promises were made to him, and this was 430 years prior to Moses’ receiving the Law from God (Galatians 3:17). However, when should we begin the countdown to Moses and the Law, and how do we know where the starting point is? Moreover, now that Abraham is dead, how does that tie into our current study of Isaac, particularly concerning Rebekah’s pregnancy with Esau and Jacob (Genesis 25:19-28)?
We understand from the text that Isaac loved Rebekah (Genesis 24:67), but being happily married after the death of his mother, Sarah, didn’t bring the anticipated peace he longed for, because Rebekah was barren, just as his mother, Sarah, had been. Rebekah was barren for 19 years, while Sarah was barren for 30 years (Genesis 25:21; cp. 11:30). Without children, Isaac couldn’t fulfill his part of the promise the Lord had given to Abraham, which pertained to becoming a great nation (Genesis 12:1-4) and producing the promised Seed (Genesis 22:18), which was Jesus, the Messiah, according to Paul (Galatians 3:16).
However, the text doesn’t clearly tell us that Sarah was barren for 30 years (Genesis 11:30; cp. 16:1-2; 18:10-12; 21:1-2). So, how can we say that Sarah was barren for that length of time? It is understood in the difference of 30 years in the scriptures (Exodus 12:40; Genesis 15:13), which concerns promises made (430 years) and the delay in their fulfillment (400 years). In other words, the time began, when the Lord called Abraham and promised that he would be given land for a possession and become a great nation is figured to be 430 years (Galatians 3:17) but the delay in the fulfillment of the promises would be 400 years from the time of Isaac’s birth, which embraces the whole length time that Sarah was barren.
We know from the text that Israel went out of Egypt 430 years after God promised the land to Abraham for a possession (Exodus 12:40), but this doesn’t mean they were in Egypt for 430 years. Rather, the time includes both the time of oppression in Egypt and the time of sojourning in the land without possessing it, vis-à-vis the sojourning of Abraham, Isaac and Jacob. So, the 430 years begins with Abraham being called out of Ur (Genesis 11:27-32; cp. Acts 7:2-4), but the 400 years begins 30 years afterward with the first of the descendants of Abraham through Sarah (Genesis 15:13; cp. 21:12).
If Isaac was born when Abraham was 100 years old (Genesis 21:5), and this was 25 years after Abraham left Haran (Genesis 12:4), then the promise, which Paul mentions (Galatians 3:17) is reckoned from Ur, where Abraham was originally called by God to a land he didn’t know. Thus, Abraham was called out of Ur, and spent 5 years in Haran, before his father died, and before we are told that he left for the land of promise in Genesis 12:1-4. Thus, the call is reckoned 430 years from Ur (Genesis 11:27-32; cp. Acts 7:2-4), not from Haran (Genesis 12:40).
Hence, Sarah was married to Abraham for at least 5 years prior to their leaving Haran, which makes sense, because we are told she was barren in Ur (Genesis 11:30). She would have had to have been married for a few years, first dwelling in Ur and then in Haran, before it could be said that she was barren. Therefore, if Abraham was 75 years old when he left Haran, he must have been 70 years old when he left Ur, which was the land out of which the Lord had originally called him (Acts 7:2).
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