Brothers and sisters:
When the fullness of time had come, God sent his Son, born of a woman, born under the law, to ransom those under the law, so that we might receive adoption as sons.

As proof that you are sons, God sent the Spirit of his Son into our hearts, crying out, “Abba, Father!”

So you are no longer a slave but a son, and if a son then also an heir, through God.