The 430 Years
We read in the Bible that the brothers of Joseph "moved with envy, sold Joseph into Egypt: but God was with him, and delivered him out of all his afflictions, and gave him favour and wisdom in the sight of Pharaoh king of Egypt; and he made him governor over Egypt and all his house" (Ac 7:9-10). Later, Joseph told his brothers:
(Gen 50:20) But as for you, ye thought evil against me; but God meant it unto good, to bring to pass, as it is this day, to save much people alive.
The Egyptians told Joseph "Thou hast saved our lives" (Gen 47:25). In addition to the Egyptians, many from other nations were saved because of Joseph, for we read that "all countries came into Egypt to Joseph for to buy corn; because that the famine was so sore in all lands" (Gen 41:57). It was because of this famine that Jacob and his sons moved to Egypt. The arrival of Jacob in Egypt marked the beginning of a 430 year period in which the descendants of Jacob lived in Egypt (Ex 12:40-41). This a significant period of time that is mentioned in various passages. In particular, the Lord spoke about it to Abraham in Gen 15:13, two hundred years or more in advance. (It is possible to see that there are at least 200 years between Gen 15:13 and the beginning of the 430 year period based on Gen 16:16, Gen 21:5, Gen 25:26, and Gen 47:9. Indeed, in view of Gen 16:16, it can be seen that Gen 15:13 happened 14 years or more before Gen 21:5, which happened 60 years before Gen 25:26, which took place 130 years before Gen 47:9, which corresponds to the time when Jacob came to Egypt.)
(Gen 15:13) And he said unto Abram, Know of a surety that thy seed shall be a stranger in a land that is not theirs, and shall serve them; and they shall afflict them four hundred years;
We read here that Israel was afflicted 400 years in Egypt. Since Israel was in Egypt for 430 years (Ex 12:40-41), it is clear that they were not afflicted the first 30 years. As we learn from various passages, the affliction of Israel became in time very severe. A possible indication of persecution in the earlier part of the 430 year period might be found in the directions that Joseph gave for his burial. He did not ask that his body be taken right away to the land of Canaan, to be buried there, as his father was (Gen 50:4-13). Rather, he told the Israelites that "God will surely visit you, and ye shall carry up my bones from hence" (Gen 50:25). The Israelites did what Joseph requested when they went out of Egypt (Ex 13:19, Jos 24:32).
The following passages speak about the persecution of Israel in Egypt.
(Act 7:17)NKJVTM "But when the time of the promise drew near which God had sworn to Abraham, the people grew and multiplied in Egypt
(Act 7:18) "till another king arose who did not know Joseph.
(Exo 1:8)MKJV And there arose a new king over Egypt, who did not know Joseph.
(Exo 1:9) And he said to his people, Behold, the people of the sons of Israel are many and mightier than we.
(Exo 1:10) Come, let us deal slyly with them, lest they multiply, and it will be when there comes a war, they join also to our enemies, and fight against us, and get out of the land.
(Act 7:19)NKJVTM This man dealt treacherously with our people, and oppressed our forefathers ...
As mentioned in Gen 15:13, Israel was afflicted 400 years in Egypt. Since only 70 descendants of Jacob were there in the beginning (Ex 1:5), and at the time of Ex 1:9 the Israelites were very numerous, it follows that Ex 1 does not describe the beginning of the persecution of Israel but rather a time when the persecution became severe.
(Exo 1:11) Therefore they did set over them taskmasters to afflict them with their burdens. And they built for Pharaoh treasure cities, Pithom and Raamses.
(Exo 1:12) But the more they afflicted them, the more they multiplied and grew. And they were grieved because of the children of Israel.
(Exo 1:13) And the Egyptians made the children of Israel to serve with rigour:
(Exo 1:14) And they made their lives bitter with hard bondage, in morter, and in brick, and in all manner of service in the field: all their service, wherein they made them serve, was with rigour.
As we read in Ex 1:12, since the people of Israel continued to grow, the persecution became more and more severe.
(Exo 1:15) And the king of Egypt spake to the Hebrew midwives, of which the name of the one was Shiphrah, and the name of the other Puah:
(Exo 1:16) And he said, When ye do the office of a midwife to the Hebrew women, and see them upon the stools; if it be a son, then ye shall kill him: but if it be a daughter, then she shall live.
(Exo 1:17) But the midwives feared God, and did not as the king of Egypt commanded them, but saved the men children alive.
(Exo 1:22) And Pharaoh charged all his people, saying, Every son that is born ye shall cast into the river, and every daughter ye shall save alive.
The verse above describes the context of the birth of Moses, which took place 80 years before the end of the 430 year period (Ex 7:7). Apparently, the decree of Pharaoh in Ex 1:22 was not enforced for a very long period of time. We would not read of people such as Joshua, Caleb, and the sons of Aaron if the decree of Pharaoh was still enforced when they were born. Moreover, when Moses appeared before Pharaoh, he never asked that the male babies be spared, which is an indication that they were no longer killed at that time. Nonetheless, the oppression of Israel in Egypt remained very severe to the end, as we read in Ex 2:23-24.
(Exo 2:23) And it came to pass in process of time, that the king of Egypt died: and the children of Israel sighed by reason of the bondage, and they cried, and their cry came up unto God by reason of the bondage.
(Exo 2:24) And God heard their groaning, and God remembered his covenant with Abraham, with Isaac, and with Jacob.
God delivers those who seek him. Now, verse 23 says only that they cried, not that they cried out to God. As we read in the Bible, at various times, Israel suffered much because they were not serving the true God. We read about Israel serving false gods in Egypt in Jos 24:14: "Put away the gods that your fathers served beyond the River and in Egypt, and serve the LORD"ESV. Moreover, Am 5:25-26 mentions that they still had false gods when they came out of Egypt. Pagan sacrifices are mentioned in Lev 17:7. Thus, in Ex 3:15, when Moses was sent back to Egypt, the Lord did not say that he was their God, but that he was the God of their fathers. They did not know much about the God of their fathers, for Moses thought that they would ask "What is his name?" (Ex 3:13). This does not mean that nobody among the people of Israel was seeking the true God. Passages mentioning Israelites seeking the true God appear in Num 20:16 and De 26:7. Now, these passages could apply to circumstances following the commissioning of Moses in Ex 3. For example, the people of Israel cried out to the Lord before crossing the Red Sea (Ex 14:10, Jos 24:7, Ne 9:9). Nonetheless, Num 20:16 and De 26:7 might refer also to people who were crying to the true God before the time of Ex 3.
(Exo 12:40) Now the sojourning of the children of Israel, who dwelt in Egypt, was four hundred and thirty years.
(Exo 12:41) And it came to pass at the end of the four hundred and thirty years, even the selfsame day it came to pass, that all the hosts of the LORD went out from the land of Egypt.
Three months after this 430 year period the people of Israel came to the wilderness of Sinai (Ex 19:1). There the law was given. Thus, in Gal 3:17, the law is literally referred to as "the-after-430-years-coming-law". Based on these observations, a precise translation of Gal 3:17 would be "But this I say: the law that came into being after the 430 years [in Egypt] does not annul the covenant that had been made before by God, so as to make the promise void".