Know that the LORD, he is God! It is he who made us, and we are his; we are his people, and the sheep of his pasture.
Following the commands to praise the LORD, we now receive our reason for praising Him: He is God! What a magnificent statement! We should praise God because He is God. In his book, Reflections on the Psalms, Lewis remarks that after becoming a Christian, he had much difficulty with the idea of being commanded to praise God. It seemed to him that God was acting like a megalomaniac, demanding praise to fuel His ego. However, read how he came to understand the nature of praise:
The miserable idea that God should in any sense need, or crave for, our worship like a vain woman wanting compliments, or a vain author presenting his new books to people who never met or heard of him, is implicitly answered by the words “If I be hungry I will not tell thee” (50,12). Even if such an absurd Deity could be conceived, He would hardly come to us, the lowest of rational creatures, to gratify His appetite. I don’t want my dog to bark approval of my books. Now that I come to think of it, there are some humans whose enthusiastically favourable criticism would not much gratify me.
But the most obvious fact about praise—whether of God or anything—strangely escaped me. I thought of it in terms of compliment, approval, or the giving of honour. I had never noticed that all enjoyment spontaneously overflows into praise unless (sometimes even if) shyness or the fear of boring others is deliberately brought in to check it. The world rings with praise—lovers praising their mistresses, readers their favourite poet, walkers praising the countryside, players praising their favourite game—praise of weather, wines, dishes, actors, motors, horses, colleges, countries, historical personages, children, flowers, mountains, rare stamps, rare beetles, even sometimes politicians or scholars. I had not noticed how the humblest, and at the same time most balanced and capacious, minds, praised most, while the cranks, misfits and malcontents praise least. The good critics found something to praise in many imperfect works; the bad ones continually narrowed the list of books we might be allowed to read… Except where intolerably adverse circumstances interfere, praise almost seems to be inner health made audible… I had not noticed either that just as men spontaneously whatever they value, so they spontaneously urge us to join them in praising it: “Isn’t she lovely? Wasn’t it glorious? Don’t you think that magnificent?” The Psalmists in telling everyone to praise God are doing what all men do when they speak of what they care about. (93-95)
Notice the two primary points Lewis makes there: enjoyment overflows into praise and all men urge others to praise what they care about. If we truly believe that the LORD is God, will we not do exactly what this psalmist is doing? Will we not beckon others to join us in praising the glories of our great God and Savior Jesus Christ?