Read: Malachi 3:6
A believer in his spiritual walk is full of variation. Sometimes his faith is at a high tide, and sometimes in a low ebb. Sometimes he is spiritually vibrant with brimming energy whereas at other times, he is in a depleted state. For some believers, their character also will be in a state of fluctuation.
But God is without any shadow of turning. The glory of God shines with a fixed brightness. He can’t change for the better or worse. He is the same yesterday, today and tomorrow. He is immutably holy, immutably good. There is no element of change in Him. You can count on Him always.