1 Praise the LORD, all you nations;
extol him, all you peoples.
2 For great is his love toward us,
and the faithfulness of the LORD endures forever.
Praise the LORD.
This is a hymn of praise. All nations are called to join Israel in a chorus of praise to YHWH, Israel's god.
This great chorus goes up because of YHWH's towering love and everlasting faithfulness displayed to Israel in his great acts of redemption. Exodus 34:6 is called to mind, especially the phrase: "abounding in love and faithfulness". (Leslie C. Allen, Word Biblical Commentary: Psalms 101-150)
Paul refers to Psalm 117 in Romans 15:7-13. Christ as a servant of the Jews has brought in the Gentiles to join with Jews to praise and extol God through Jesus the Messiah. All nations are now included and this psalm is now fulfilled.
As we gather as the community of Jesus in our various gatherings and lift up our voices in song, let's consider ourselves part of one mighty chorus that includes all who belong to Jesus: past, present and future. Let's also consider that time to be a call to worship, calling others to join with us in praise of our God, and of his great goodness to us in Jesus.