Psalm 148 gives the amazing grace of being as the rationale for praising God.

The last five psalms in the Book of Psalms are known as the Hallelujah psalms. That’s because each starts and ends with the word Hallelujah, which in Hebrew means “Praise the Lord.”
Why praise the Lord, however? The five psalms give different answers. The answer given by Psalm 148 is one we might not expect. It comes in verses 3 through 5. There the psalmist summons the heavenly bodies–sun, moon, and shining stars–to join the angelic choirs in singing God’s praises.
But why? Because God commanded and they were created (Psalm 148:5). They are to praise God because God summoned them into being.
This turns out to be a rationale for praising God for not only the heavenly beings, but for every existing thing, including us humans. The psalmist calls upon all creation, including us, to praise God just because all creation exists. This summoning into being is a gift, in fact, one of God’s greatest gifts to all that is.
I say it is a great gift because the alternative is not to be. If we had never been, we would have missed out on this great privilege of being alive and a part of this splendid creation that God is making.
God considers it important that each one of us be a part of this great work, and so he summons us into being. I know that life can bring many disappointments, sufferings, and sorrows, but I wonder how many of us pause now and them to remind ourselves of what an astonishing gift it is to just be.
The Question Science Can’t Answer
Science tells us a great deal about how the universe and living things came into being. They say it all began about 13 and a half billion years ago with a stupendous, big, explosive bang.
They have mapped out the many evolutionary stages that that expanding universe has gone through in the billions of years since to bring us to the amazing planet on which we now live with all its teeming life.
But there is one thing I am convinced that science cannot answer. That is the question Why? Why does the world exist? Why do we exist? What is the universe’s meaning? What is its–and our–purpose?
Science is not able to answer that question. In fact, many scientists today, relying only on scientific observations, will tell us that the universe has no meaning. So human beings must turn to philosophy and religion to find an answer.
I believe that Christianity has an answer to this question Why? The answer is: Because of the overflowing love of God. The God we acknowledge is one who out of love creates because it gives God pleasure and God wants to share that pleasure with an abundance of other material and living beings.
When my Presbyterian heritage asks the question–“What is the chief end of human beings?”–it answers it with a statement of faith–“To glorify God and enjoy God forever.” God creates the universe–and each one of us individually–so that we can all share in his life of super-abundant love. Creation gives God delight and God can’t keep that delight to God’s self.
That is a compelling reason for the invitation to praise God that the psalmist issues to us. Let everything that is praise the Lord.