Therefore, brothers, we are not children of the slave but of the free woman.
Fundamentally it seems to me that Paul is saying that we are no longer slaves of the flesh but instead sons of the Spirit of Christ.
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.’
The slaves of the flesh are marching to their death while trying to manage their behavior through a system of lifeless laws. The sons of Christ are truly free and enjoy this freedom from the tyranny of the flesh now and forever. Through faith in Christ we are made sons of Freedom and it is for Freedom we have been set free. No other ‘faith system’ offers such or comes anywhere near it. Every other faith system simply offers a different form of slavery to the flesh through a legalistic adherence to rules and regulations that do not bring freedom. Christianity alone offers true freedom from the slavery of the flesh and the burden of religious obligation.
Thanks be to the God of all grace!