The first verse of Psalm 136 sets the tone for everything that follows, for it gives an overall answer to the question, Why should we thank God? The answer is that we praise him because he is good. We thank him for his many good acts toward us and to all persons. 

Are not other gods also to be worshiped? How could they be if God alone is the good, great, gracious, persevering and unchangeable God? Verses 15-18 make this point, contrasting the true God with the impotent gods of the heathen. These verses are repeated from Psalm 115:4-6, 8. 

The heart of Psalm 135 is the four stanzas covering verses 3-14, for it is in these verses that God is actually praised. He is praised because he alone is praiseworthy. The verses give reasons why, introducing several of them (though not all) by the word “for”: “Praise the LORD, for the LORD is good" (v. 3); “For the LORD has chosen Jacob to be his own" (v. 4); and “For the LORD will vindicate his people” (v. 14). The King James Version also used the word to introduce verse 5. The psalm gives us at least five reasons why God is praiseworthy.

For the last fifteen psalms we have been studying the Songs of Ascents (Pss. 120-134), those well-known psalms that seem to have been sung by Jewish pilgrims as they made their way to Jerusalem for the three annual feasts that adult Jewish males were required to attend. With Psalm 135 we begin a new and also final section of the Psalter (Pss. 135-150), which emphasizes the worship or praise of God specifically. It is a psalm that tells us who should worship God and why. 

If we are to worship God, we must get to know God, and this means that we must begin to study God's own revelation of himself in the Bible. Every Christian must do this. If we are to praise and glorify God as we ought, we will have to watch television less and study God's Word more. We will have to become men and women of the Book.