When i was at New Wine there was a guest speaker doing a seminar on one of the evenings, and it looked interesting so i decided to go, she was talking about how God is unchangeable and how he is forever the same. It was really good how she explained it and went through the reasons why he is unchangeable.
She explained about what it means to change, so, say if someone or something changed, they'd either changer for the better or the worse. But think about it, were talking about God now, so if God changed, then he would either change for the better or the worse, if he changed for the better then that would mean that he wasn't good enough in the first place but it says in the bible...
"As for God, his way is perfect; the word of the LORD is flawless." Psalm 18:30 and "...therefore, as your heavenly Father is perfect." Matthew 5:48.
So we've now established that God cannot change for the better because he is already perfect and far more than good enough, he couldn't be any better! Also God cant change for the worse because that would mean that he must have slipped up somewhere, somehow. He must have done something wrong that has caused him to not be quite as perfect. But he is perfect, as it says in the scriptures above, the bible also says,
"...the gospel did not come to you in word only, but also in power, and in the Holy Spirit and in much assurance..." 1 Thessalonians 1:5. His word is true.
It says in Hebrews 13:8, "Jesus Christ is the same yesterday and today and forever."
God is perfect, holy, spotless, amazing and unchangeable! and he always will be!