How do we know that God removes our transgressions?

Psalm 103:12 illustrates the complete removal of our sins by depicting the immeasurable distance from east to west. This imagery signifies that God has not only forgiven our sins but has also chosen to forget them entirely, as affirmed in Jeremiah 31:34, where God promises, 'I will forgive their iniquity and I will remember their sin no more.' This speaks to the effectiveness of Christ's sacrifice, which encompasses all our transgressions and secures forgiveness for those whom God has elected.