God has saved us and called us to live a holy life. This isn’t because of anything we’ve done, but because of his own purpose and grace. This grace was given to us in Christ Jesus even before time began.
But even before her twins were born, before they’d done anything good or bad, Rebekah was told, “The older son will serve the younger one.” This shows that God’s purpose was based firmly on his own choice, not on anything the children did.