Because you are his sons, God sent the Spirit of his Son into our hearts, the Spirit who calls out, “Abba, Father.”
The idea of slavery is a concept that though understood is foreign to our experience. Total submission and commitment were demanded of a slave. A slave was property rather than a person. He was at the mercy of his master. He was completely disposable. If age, sickness, weakness, or disobedience became a source of irritation to the slave owner, the master would not hesitate to sell or take the life of his slave.
There have been cases, however, where slaves have been freed by their masters. Although it has not been a common occurrence, some have even been adopted into the master’s family. In the Roman culture if a slave was adopted it meant that he became a citizen, his debts were paid, his family alliance was changed, and he became an heir to the master’s wealth. He was no longer a slave. He was now a son.
This is what takes place when we are delivered from the slavery of sinfulness. We become a citizen of heaven, the judgment of sin against us is cancelled, our allegiances to our former life and associations are changed, and we become a joint heir with the Son of God. We are no longer slaves but children of God.
Dr. Gayle Woods