If you believe that God can change, where is your hope? If the God of the Bible can change, who can you trust? Someone once told me that the God of the Old Testament was mean and nasty, I've got news, that is the same God we are living with today. God does not change! We are the ones that shift and are not fixed - our minds vary so we attach that way to God because that's our perception. Not only is He unchanging, but He is also all knowing, which means that He also knows the way that He will act according to our obedience or disobedience. He may give us the opportunity to repent before calamity happens, and it may seem to us that He change His mind, but we are the ones who made a choice. God is loving but He is also just. You can't continue in your sin and expect that you won't have to pay a price for that sin. He wouldn't be perfect and holy if He could be less than holy and then go back to being holy.
Jesus Christ is the same yesterday and today and forever. Hebrews 13:8