Exodus 12:40-42 - "Now the sojourn of the children of Israel who lived in Egypt was four hundred and thirty years. And it came to pass at the end of the four hundred and thirty years--on that very same day--it came to pass that all the armies of the LORD went out from the land of Egypt. It is a solemn observance to the LORD for bringing them out of the land of Egypt. This is that night of the LORD, a solemn observance for all the children of Israel throughout their generations."
Galatians 3:16-18 - "Now to Abraham and his Seed were the promises made. He does not say, 'And to seeds,' as of many, but as of one, 'And to your Seed,' who is Christ. And this I say, that the law which was four hundred and thirty years later, cannot annul the covenant that was confirmed before by God in Christ, that it should make the promise of no effect. For if the inheritance is of the law, it is no longer of promise; but God gave it to Abraham by promise."
Both passages mention a timeframe of 430 years. However, Moses seems to state that the Israelites lived in Egypt for this entire duration while Paul seems to affirm that the 430 year period spanned the time from the giving of the promise to Abraham up until the exodus, which would make the years lived in Egypt much fewer than 430. So, who is correct: Moses or Paul? That's not the right question, of course. Both men were inspired writers (cf. II Tim. 3:16,17) and both are correct, but there must be some explanation as to this apparent discrepancy.
Although there are those whom I respect greatly who disagree with me on this point, it is my studied conviction that it was only 215 years from the migration of Jacob into Egypt until the exodus led by Moses. How did I arrive at this figure? Allow me to explain.
If we start with Galatians 3:17, where we are told that the promise given to Abraham until the exodus is precisely 430 years, we first assume that the promise mentioned in Genesis 12 is in view where Abraham was 75 years old (cf. Gen. 12:4) and that he also presumably lived some in Egypt as a nomad that same year (cf. Gen. 12:10). Isaac was born 25 years later (i.e., when Abraham was 100; cf. Gen. 21:5). Jacob was born 60 years later (cf. Gen. 25:26). And Jacob and his family moved to Egypt 130 years later (cf. Gen. 47:9). Thus, if we take 25 + 60 + 130, we get 215 years from the giving of the promise to the migration of Israel into Egypt. When we subtract 215 from 430, we are left with 215, which is the number of years the Israelites lived in Egypt from Jacob to the exodus.
I believe the above reasoning can account for the wording of Exodus 12:40-42, especially if there is any merit in the Septuagint translation here, which states that the 430 year period covers the sojourn of the Israelites while they lived in both Egypt and Canaan (which would match perfectly with Paul's figure). Even without the Septuagint, however, we have shown that Abraham lived in Egypt himself for a time very soon after the promise was given. So, there is a sense in which the nation of Israel (which began with Abraham [cf. Gen. 12:2] though it was not named after him) had sojourned in Egypt over a 430 year span (though not continuously for 430 years). Technically, they lived as foreigners in both Canaan and Egypt for that duration.
Furthermore, this view explains other related chronological information given in Genesis 15:13,14 - "Then He said to Abram: 'Know certainly that your descendants will be strangers in a land that is not theirs, and will serve them, and they will afflict them four hundred years. And also the nation whom they serve I will judge; afterward they shall come out with great possessions'" (cf. Acts 7:6). The typical explanation offered here by commentators is that Moses was rounding down from 430 years to 400, but I do not believe this is correct. Moses was very precise elsewhere (e.g., Gen. 5; 11; Num. 1; etc.). Why would he round here?
If we calculate Isaac's age 400 years before the exodus, I believe we will find our solution. From the passages noted previously, the promise was given to Abraham when he was 75 and Isaac was born 25 years later. Thus, Isaac was 5 years old when the 400 year time period began. Is there anything that happened to Isaac at that age that could be considered affliction? Genesis 21:8,9 records Ishmael (who was part Egyptian) mocking Isaac after he was weaned. Paul even uses the word "persecuted" in Galatians 4:29 when referring to Ishmael's treatment of Isaac. This affliction could have happened when Isaac was 5 years old. And 400 years later the Israelites, who, like Isaac, lived as strangers in a foreign land, would escape all servitude to the Egyptians through Moses! This would happen four generations after the migration to Egypt started (cf. Gen. 15:16; i.e., Levi, Kohath, Amram, & Moses; cf. Exo. 6:14ff).
We will continue this study in our next lesson.