How do we know that God's mercy changes us?

The transformation brought by God's mercy is fundamental to sovereign grace theology. According to 2 Corinthians 5:17, if anyone is in Christ, he is a new creation; old things have passed away, and all things have become new. This change is not merely behavioral but is an internal heart transformation where believers are regenerated and given a new desire to honor and love God. This is rooted in the deep mercies of God, as exemplified by the characters of David and Job, whose uprightness is attributed to God's mercy rather than their intrinsic goodness.