The understanding that God is immutable in general is shared with other Christians.  For example, from this Evangelical site:

Third, the immutability of God is related to His omniscience.  When someone changes his/her mind, it is often because new information has come to light that was not previously known or because the circumstances have changed and require a different attitude or action.  Because God is omniscient, He cannot learn something new that He did not already know.  So, when the Bible speaks of God changing His mind, it must be understood that the circumstance or situation has changed, not God.  When Exodus 32:14 and 1 Samuel 15:11-29 speak of God changing His mind, it is simply describing a change of dispensation and outward dealings toward man.

https://www.gotquestions.org/immutability-God.html

One aspect of this quote from the Evangelical site I would question a bit is the idea when Scripture speaks to God changing His mind, “it is simply describing a change of dispensation and outward dealings toward man.”  I think that could be interpreted in a way that is consistent with Catholic understanding, but also could be problematic.  If God does not change, can the way He “outwardly” deals with us change?

Consider the story in found in Exodus 32:9-14.  God has saved the Israelites from slavery in Egypt, and then brought them into the desert.  When God calls Moses to the mountain, the Israelites use the opportunity to revert to the idol worship they had learned in Egypt.  They create a golden calf to worship, and the story tells us that God then wants to destroy the Israelites.  He calls them “a stiff-necked people,” and He wants instead to create a great nation from Moses.  Moses pleads with the Lord to spare them, and because of his prayer, “the Lord repented of the evil which he thought to do to His people.”

Remember some of the other characteristics we believe to be true about God.  First, He is omnipresent, meaning He exists in all moments of time eternally.  He is also omniscient, meaning He has complete and total knowledge throughout time.  So even when God was bringing the Israelites out of Egypt, He knew that in the desert they would again turn to idol worship.  He knew that Moses would intercede on their behalf.  He knew that He was not going to destroy them.

So why the exchange?  It’s also important to remember that God has no need .  This exchange is not about something God needs in order to change His mind.  It is completely about something that Moses needs, and that’s how we should always understand these passages in Scripture.  What need of ours is being met?  What lesson are we learning?  How are we growing in charity?

That does not mean that the actions of Moses were not important to the fact the Israelites were spared.  Many gifts we receive are through prayer, and Moses plea to God did indeed save them.  We just need to realize that God had no decision to make, for there also was never a time He did not know that Moses would pray for God to spare them, and through that prayer Moses would receive their lives.  God never makes decisions whereby He moves from a state of not knowing what He will do in one moment, and then another state of knowing.  He is “I am who am.”

Why is this topic that important?  This topic has major implications on what we believe and why we believe it.  First, it is not possible that God changes.  He is perfection of existence and Being for all eternity.  And everything we believe should always be “tested” to ensure it does not contradict this eternal truth.  For example, if our understanding of salvation is that when we accept Christ, we cause God to change the way He views us, then the eternal God would be subject to change based upon something we do.  We always need to understand that the person who changes in our relationship with God is us, whether in a positive or negative way.  In my next post I’ll give a practical example of how this should influence what we believe and how.