The sermon explores Paul's argument in Galatians 3, emphasizing that faith in Christ, not adherence to the Mosaic Law, is the pathway to becoming a son of God. It examines the temporary nature of the law, highlighting its role as a guardian leading to Christ, and underscores the significance of baptism as a symbol of union with Christ, resulting in a new identity as heirs of God, free from bondage and united in Christ, regardless of ethnic or social background. The preacher stresses the importance of understanding that faith, not legalistic observance, is the means by which believers receive the Holy Spirit and are incorporated into God's family, experiencing His love and inheritance.