"So the Lord changed His mind about the harm which He said He would do to His people," (Exodus 32:14, NASB).
Different Bible's translate this verse differently. The NASB says, "the Lord changed His mind." The NIV and NKJV say "The Lord relented." The KJV, RSV, and the 1901 ASV say, "The Lord repented." The Hebrew word at issue here is relent/repent is נָחַם (nacham). There are 108 occurrences in the Old Testament. The KJV translates it as "comfort" 57 times, "repent" 41 times, "comforter" nine times, and "ease" once.
The issue, of course, is whether or not God actually goes through a process of changing His mind due to learning something, as the open theists would maintain. But, is God actually reacting to knew "Turn from Thy burning anger and change Thy mind about doing harm to Thy people. 13'Remember Abraham, Isaac, and Israel, Thy servants to whom Thou didst swear by Thyself, and didst say to them, 'I will multiply your descendants as the stars of the heavens, and all this land of which I have spoken I will give to your descendants, and they shall inherit it forever. 14So the Lord changed His mind about the harm which He said He would do to His people," (Exodus 32:12-14, NASB).
First of all, it is apparent that Moses disobeyed God's instruction to leave Him alone (v. 10). Instead of Moses listening to God, he pleads with God to spare Israel and God relents. Why? What is the significance of God allowing Himself to be swayed by the interceding work of Moses on behalf of Israel? Why did God not ignore Moses' request and go ahead and destroy the nation? The answer is simple: because of Jesus. Jesus said inJohn 5:39, "You search the Scriptures, because you think that in them you have eternal life; and it is these that bear witness of Me." Jesus says the Bible is about Him. Certainly, such an important figure as Moses must reflect Jesus in some way, and he does. As Moses interceded for his people, Jesus also intercedes for His. God listened to Moses because God would listen to Jesus.
Second, we must ask if God was or was not aware of the condition of the hearts of the people of Israel. Open theism states that God knows all of the present exhaustively, including the attitudes and thoughts of all people. Now, didn't God know the hearts of the people? Didn't He know they were ready for idolatry? Are we to believe that God didn't know there were going to be a host of Jews who would most certainly fall into idolatry if Moses was up on the mount too long? It seems so, yet God allowed them the time necessary to fall into idolatry. Moses then ordered the Levites to kill those who opposed God, and about 3,000 fell that day (Exodus 32:28). It is interesting to note that in Acts, when Peter preached and the Spirit of God moved on people and they were saved, 3,000 were added that day to the church (Acts 2:41). When the Law was given, 3,000 died. When the gospel was given, 3,000 were saved.
Third, God often waits until something happens before He "makes His move." In the Garden of Adam and Eve, God waited to come on the scene until after Adam and Eve sinned. God promised Abraham he would be the father of a great nation, but waited until after Ishmael was born before he allowed Abraham to have Isaac. Jesus waited until Lazarus died before going to resurrect him. In fact, Jesus' incarnation did not occur until the time of Roman oppression and Pharisaical legalistic apostasy. Can we not also expect that God had Moses wait on the Mount until the people of Israel fell into idolatry so that He might desire to exterminate them, and so that Moses might intercede (as a type of Christ), so that God might show His mercy? Notice how the intercession of Moses is an appeal to the grace of God in face of the Law of God, which had already been given. The Law of God said not to commit idolatry (Exodus 20), yet the Israelites did just that. It was not until after the Law was given to Moses that their sin was to be judged and the intercession of Moses occurred. As Amos 3:7 says, "Surely the Lord God does nothing unless He reveals His secret counsel to His servants the prophets." God reveals His will and plans in types and symbols in the Old Testament. These types and symbols point ahead to Jesus, of which Moses was a type.
We see that the Hebrew word for "repent, relent, change," etc. is nashash, which has a scope of meaning, which we see in other translations, that can infer God's change of direction and purpose towards a people.
We see that Moses was a type of Christ demonstrating the intercessory work of Christ, to which God would listen.
God must have known the present condition of the Jews and would have known they were going to commit idolatry, yet He kept Moses on Mt. Sinai until after their sin. This had to be done for a purpose, both to demonstrate the Law of God for those who were destroyed and the mercy of God upon those who repented.
If God changed His mind, in that He adapted to new information, then God does not know all things (1 John 3:20), did not even know the then-present condition of the Israelites, waited too long with Moses on Mt. Sinai, and was influenced by Moses who disobeyed God's command to leave Him alone. It would make more sense to say that God waited for a reason, threatened to destroy Israel, and allowed Moses to intercede on their behalf so they would be saved.