“Divine election is the guarantee that God will undertake to complete by sanctifying grace what his electing grace has begun. This is the meaning of the new covenant: God does not merely command obedience. He gives it.
“The Lord your God will circumcise your heart and the heart of your offspring, so that you will love the Lord your God with all your heart and with all your soul, that you may live” ( Deuteronomy 30:6 ). “I will put my Spirit within you, and cause you to walk in my statutes” ( Ezekiel 36:27; 11:20; see also Hebrews 13:20; Philippians 2:13).
Election is the final ground of assurance because, since it is God’s commitment to save, it is also God’s commitment to enable all that is necessary for salvation.”
-John Piper, The Pleasures of God: Meditations on God’s Delight in Being God, 134.