Under the old covenant administration, Israel’s worship and life were intended not only for that chosen nation but for the entire world. That is, God did not call Israel to have a narrow focus on itself and its own relationship to Him but to be conscious of how this relationship would be a light to the nations. Consider Deuteronomy 4:1–8. Moses’ exhortation for obedience and its connection to blessing has in view the notion that as Israel worshiped and served the Lord rightly, the Lord would be quick to answer the prayers of the nation. Such supernatural action, in turn, would cause the Gentile nations to consider the source of this blessing—the one true God (v. 7). Furthermore, Israel’s faithfulness to the law of God would lead the world to think on the source of these righteous statutes—the one true God (v. 8).
It is not that there was a precise, mathematical one-to-one correlation between obedience and blessing. The Bible knows nothing of a mechanically reciprocal relationship between God and His people that eliminates His freedom to bless as He sees fit. Still, corporate obedience carried with it the promise of corporate blessing (Deut. 28:1–14). As Israel obeyed, the nation would experience divine favor and blessing, evidence of God’s covenant faithfulness. In that respect, Israel’s understanding and worship of the lord for His faithfulness was tied to the nation’s faithfulness. Thus, in one sense, Israel would be unable to announce God’s faithfulness as commended in Psalm 117 if she was unfaithful.
The Bible emphasizes divine grace as the initiator and sustainer of even the meager faithfulness that sinners express toward the Lord, so Israel’s faithfulness, when it occurred, was always a testimony to this grace. However, God revealed His steadfast love and faithfulness in greatest measure to the nations during the old covenant period in His grace shown to Israel even when she fell. The true depth of the Lord’s love was seen in the preservation of Israel as a nation even when she was least deserving of it (Jer. 31:1–3). Similarly, our Creator’s faithfulness to His Word is seen today as He sustains His church despite our sin.
Ultimately, God’s covenant love to undeserving sinners was the greatest testimony to the nations of His truth under the old covenant, so the psalmist in today’s passage exhorts the world’s nations to praise Him for such steadfastness. When we repent of our sin, we show the Lord’s faithfulness to forgive and thereby implore the nations to serve Him.