Know therefore that the Lord your God is God, the faithful God who keeps covenant and steadfast love with those who love him and keep his commandments, to a thousand generations,” (Deuteronomy 7:9, ESV)

Moses to his fellow Israelites.

God is faithful. This means that the covenant into which God had entered with his people would be upheld by God.  The people did not need to worry about God capriciously deciding that he no longer wanted to keep the covenant, on his part, he was faithful.

The requirement for God’s people was that they in return love God and keep his commandments.

Then this beautiful phrase: to a thousand generations.   This God, the God who had entered into a covenant with his people would stand by his covenant for a thousand generations.  This is like saying that he would be faithful to the covenant that he had made to eternity and beyond.  Years would come and go, nations would arise and fall, people would live and die, time would march ever onward in an unrelenting stream, and God would stand faithful to his covenant with no change and no hesitation.

When we come to faith in Christ, we enter into a relationship with God in which he promises the same faithfulness to us that he had to the Israelites.  He will not waver; he will not change; he will not falter in his love and care for us to a thousand generations.

Or, as the writer to Hebrews puts it:

Let us hold fast the confession of our hope without wavering, for he who promised is faithful.” (Hebrews 10:23, ESV)