But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. And because you are sons, God has sent the Spirit of his Son into our hearts, crying, “Abba! Father!” So you are no longer a slave, but a son, and if a son, then an heir through God (Galatians 4:4-6)
Every newborn baby has its own distinctive cry. So, too, do the children of God. And we know we’re children of God when we cry in a certain way. We know we’ve been adopted into God’s family when we respond to the circumstances in our lives with the cries of intimacy and dependence. We know we are sons or daughters of God when we look to our heavenly Father in time of need with confidence and trust. We know we’re his children when we find ourselves crying out, “Abba! Father!”
This isn’t something we manufacture in our own strength; this distinctive cry of the children of God is something God himself causes to well up within us by his Spirit—the Spirit of his Son—whom he sends into our heart when he adopts us as his children. This is how we know we’ve been adopted; this is how we know we are children of God. And if we are children of God, then we are heirs through God.
Adapted from Galatians: Gospel-Rooted Living by Todd Wilson