Paul, in his letter to the Galatians , says Christians became sons of God by

According to Paul in his letter to the Galatians, Christians become sons of God through adoption. Adoption is the process by which a person is legally and permanently made a member of a family to which they do not biologically belong. In the spiritual sense, adoption means that through faith in Jesus Christ, believers are made part of God's family and have the same status as His biological children. This adoption is made possible by the sacrificial death of Jesus on the cross, which makes forgiveness of sins and reconciliation with God possible. Through this adoption, believers receive the Holy Spirit as a guarantee of their inheritance and can call God their Father. Therefore, Christians are not sons of God by their own merit or good deeds, but by God's grace and adoption through faith in Jesus Christ.