When investigating seemingly contradictory statements in the Bible, it's critically important to remember that our thoughts and understanding pale in comparison to God.
For my thoughts are not your thoughts, neither are your ways my ways, declares the LORD.
— Isaiah 55:8
For the foolishness of God is wiser than men, and the weakness of God is stronger than men.
— 1 Corinthians 1:25
Men cannot understand the God of the universe in all of His magnitude, we simply are not capable of this understanding. While we are able to know God, our knowledge of Him and how He works will never be complete. His nature exceeds all that we can fathom, He has only given us what we ought to know about Him now.
However, we are made in His image, therefore we have the capacity to understand the things He reveals to us, especially with the Holy Spirit as our helper.
When God speaks to mankind, He does so either communicating clearly in a way that we understand or He does so in a way in which He only wants some people to understand. See Matthew 13:10-17.
Additionally, God's word contains many examples of phenomenological language (the illusion or appearance of something in "the way that we see it"). We must exercise caution to avoid taking things out of context to ensure that we get a full and rich understanding of the truth.
From the perspective of the reader, it appears that the Bible declares that God is immutable, sovereign and yet also refers to God regretting and relenting in certain situations:
God is immutable and does not change His mind:
God is not man, that he should lie, or a son of man, that he should change his mind. Has he said, and will he not do it? Or has he spoken, and will he not fulfil it?
— Numbers 23:19
“For I the LORD do not change; therefore you, O children of Jacob, are not consumed.
— Malachi 3:6
Every good gift and every perfect gift is from above, coming down from the Father of lights, with whom there is no variation or shadow due to change.
— James 1:17
God is Sovereign:
[Our Lord Jesus Christ] who is the blessed and only Sovereign, the King of kings and Lord of lords.
1 Timothy 6:15b
They cried out with a loud voice, “O Sovereign Lord, holy and true, how long before you will judge and avenge our blood on those who dwell on the earth?
— Revelation 6:10
God can do whatever He pleases, everything is through Him and because of Him:
Our God is in the heavens; he does all that he pleases.
— Psalm 115:3
In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will.
— Ephesians 1:11
So then he has mercy on whomever he wills, and he hardens whomever he wills.
— Romans 9:18
Instead you ought to say, "If the Lord wills, we will live and do this or that.
— James 4:15
Examples of God grieving and relenting:
And the LORD regretted that he had made man on the earth, and it grieved him to his heart.
— Genesis 6:6
And the LORD relented from the disaster that he had spoken of bringing on his people.
— Exodus 32:14
If at any time I declare concerning a nation or a kingdom, that I will pluck up and break down and destroy it, and if that nation, concerning which I have spoken, turns from its evil, I will relent of the disaster that I intended to do to it.
— Jeremiah 18:7–8
Who knows? God may turn and relent and turn from his fierce anger, so that we may not perish.” When God saw what they did, how they turned from their evil way, God relented of the disaster that he had said he would do to them, and he did not do it.
— Jonah 3:9–10
How can all of these statements be true at once?
There are a few things that we need to begin unpacking here. The best place to start is at 1 Samuel 15:11 where it says:
I regret that I have made Saul king, because he has turned away from me and has not carried out my instructions.” Samuel was angry, and he cried out to the Lord all that night.
and 1 Samuel 15:35 where it also says:
Until the day Samuel died, he did not go to see Saul again, though Samuel mourned for him. And the Lord regretted that he had made Saul king over Israel.
At first glance, this seems to prove that God has regretted and changed His mind on his appointment of Saul as king. However, in 1 Samuel 15:29:
And he who is the Glory of Israel will not lie, nor will he change his mind, for he is not a man that he should change his mind!
In Samuel the writer uses the Hebrew word "נָחַם" i.e., "nacham" which has the same meaning, regret, change mind etc. However, the hint remains within 1 Samuel 15:29 where God states that the Glory of Israel "will not lie, nor will he change his mind". God cannot lie, He always speaks the truth. Therefore, we can say that God literally never changes His mind. It may appear as a change of mind, but the appearance of a change of action is not the same as changing ones mind.
From a human perspective, it is difficult to wrap our heads around this. But consider it this way, if God was to change His mind or go against His own word - He could no longer be considered trustworthy.
While at first glance, these verses appear to be contradicting each other, it is not actually the case.
God knows the future. In fact, He places His authority on the matter in Isaiah.
Remember this and stand firm, recall it to mind, you transgressors, remember the former things of old; for I am God, and there is no other; I am God, and there is none like me, declaring the end from the beginning and from ancient times things not yet done, saying, ‘My counsel shall stand, and I will accomplish all my purpose,’ calling a bird of prey from the east, the man of my counsel from a far country. I have spoken, and I will bring it to pass; I have purposed, and I will do it.
— Isaiah 46:8–11
God is the only being that can declare the beginning from the end. Logically therefore, we can suppose that God already knew the outcome of every situation. If this be the case, then God has not changed His mind, but has used promises to instil Godly fear which turns the nations back to Him. We see this play out throughout multiple examples in the Old Testament.
The Old Testament passages where God appears to repent, or change His mind almost always deal with threats of judgement, of which are followed by repentance of the people, or intercessory petitions of their leaders. God is not changing His mind, simply doing what He had already promised to do. He will not punish sinners that repent and turn away from their evil. He is simply fulfilling His promises.
It is not that God is changing His mind, although it may appear so from our perspective. God has already made promises of grace for people that turn from their sinful lives.
The point of these passages are to help us realise Christ's intercessions that allows us to live in grace. It should bring us back to prayer and bring us to repentance from our sinful nature.