The purpose of praise is two-fold. First it's a proper thing to do. God is worthy of our praise. When we praise God we're not gilding the lily. We're not engaging in flattery. God doesn't need our praise. He is not insecure or needy. He is worthy of all our praise. It is good, right and salutary that we should praise God.
We also praise God as a witness to the nations. We're calling attention to God, that he is above all powers, all other gods, and beyond any other source of good and blessing. It may be that people will dismiss our praise as emotional froth. But it is not. And honorable women and men will recognize the truth of what we proclaim. God is good. His steadfast love endures forever. His faithfulness spans generation after generation.
