Sonship is the family identity God gives to those in Christ: through the new birth and adoption, believers become God’s children and share the life and inheritance of the Son.
We are not merely pardoned servants but received children — born of God and adopted into His family, able to cry, Abba, Father. Christ alone is the eternal Son by nature. Those united to Him become God’s children by grace and share His family standing and promised inheritance; they do not become divine or sons in the same way He is.
See in Scripture: John 1:12–13; Romans 8:14–17; Galatians 4:4–7; 1 John 3:1