Galatians 4
An hier who is a child is no different to a slave because they are under guardianship and stewardship, until the appointed time of the father. Similarly, we were slaves to the world when we were children until God sent Jesus through a woman to redeem us from the law to receive the adoption as sons of God (joint-heirs with Christ).
Now that we are sons of God/ heirs of God through Christ, we are no longer slaves, rather we have the spirit of God in our hearts.
There are 2 covenants: the covenant of the law (flesh) and the covenant of the blood (promise). This is demonstrated with Abraham and his 2 sons: Issac and Ismeal. Ismeal was born according to flesh (law) and Isaac was born according to the Spirit (Jesus).
The covenant of the law represents bondage as it makes us slaves to the world (Satan) however the covenant of the Spirit represents freedom from the law and children of the promise, like Isaac.
Therefore, everything that Christ has, now belongs to us by inheritance