II Chronicles 21:7 Howbeit the LORD would not destroy the house of David, because of the covenant that he had made with David, and as he promised to give a light to him and to his sons for ever.
God was angry but He kept His Word. This was a perfect opportunity for God to change His mind. He could have said, that is it! I now change what I said but He didn’t. He kept His Word though men weren’t doing what He commanded.
He kept His Word because He had made a promise. That should give you great security. God’s people weren’t doing what God want them to do. They were actually angering Him but He still kept His Word.
You can know your salvation is secure not because of any thing you do but because He is a God of integrity. He is honest. He keeps His Word even when we don’t.
If we are not faithful He is faithful still!