The psalm opens with an exhortation, maybe offered by the worshippers at the temple concerning those working for God within it (vv. 1-2). They wanted those workers to enjoy praising God – they describe such praise as good and pleasant. It is good because it is right and it is pleasant because it is enjoyable.
They had many reasons for praising God. One was his sovereign selection of Israel as his people (v. 4). Another was his sovereign control of the created order (vv. 5-7). A third was his acts in history on behalf of his people – in verses 8-12 the author repeats what happened at the Exodus as an encouragement to expect great things from God.
They could also praise God for what he will do in the future (vv. 13-18). Unlike the dumb idols of the nations, the Lord will yet vindicate those who worship him. The idols, because they are non-existent, cannot do anything for those who serve them. Idols are only an extension of those who make them and merely reflect the desires of their makers. In contrast, the Lord is eternal and he will always do great things for his people.
Verses 19-20 indicate that the worshippers saw their song as containing topics that would encourage those who served the Lord in a full-time way. The same reasons can be used as encouragement for contemporary servants of God and it is important for other Christians to remind them of who God is and what he has done for his cause in the past. We should remind one another that our God has eternally loved his people, that he is in control of the universe today, that he has delivered his cause countless times in the past, and that he has wonderful plans for them as they anticipate an endless future of divine blessing.
It is not surprising that those who sang the psalm closed it with a strong affirmation of praise for the Lord (v. 21). The important aspect of Israel’s situation was that their God dwelt with them in Jerusalem. His care and his provision was not given from a detached location. And his care and provision for us is even more intimate. Therefore we should imitate them and bless our God.