Definition and Concept
Spiritual adoption is a theological concept referring to the act of God by which believers in Jesus Christ are received into His family as His children. This adoption is not based on human merit but is a gracious act of God, signifying a change in the believer's status and relationship with God. It is a central theme in the New Testament, illustrating the transformation from being outside of God's family to becoming His sons and daughters.

Biblical Foundation
The concept of spiritual adoption is primarily found in the writings of the Apostle Paul. In Romans 8:15, Paul writes, "For you did not receive a spirit of slavery that returns you to fear, but you received the Spirit of sonship, by whom we cry, 'Abba! Father!'" . This verse highlights the intimate relationship believers have with God, characterized by the term "Abba," an Aramaic word for father, denoting closeness and affection.

In Galatians 4:4-5, Paul further explains, "But when the time had fully come, God sent His Son, born of a woman, born under the law, to redeem those under the law, that we might receive our adoption as sons" . Here, the purpose of Christ's incarnation and redemptive work is linked directly to the believers' adoption, emphasizing that it is through Jesus that this new relationship is made possible.

Theological Implications
Spiritual adoption carries profound theological implications. It signifies a change in identity and status for the believer. As adopted children, believers are no longer slaves to sin but are heirs of God and co-heirs with Christ (Romans 8:17). This new identity comes with privileges, such as the indwelling of the Holy Spirit, who testifies to our spirit that we are God's children (Romans 8:16).

Moreover, adoption implies a future inheritance. Ephesians 1:5-6 states, "He predestined us for adoption as His sons through Jesus Christ, according to the good pleasure of His will, to the praise of His glorious grace, which He has freely given us in the Beloved One" . This passage underscores that adoption is part of God's eternal plan, and it is through His grace that believers are brought into this familial relationship.

Practical Outworking
The reality of spiritual adoption should influence the believer's life and conduct. As children of God, believers are called to live in a manner worthy of their new identity. This includes exhibiting love, obedience, and holiness, reflecting the character of their Heavenly Father. In 1 John 3:1, the apostle John marvels at this reality: "Behold what manner of love the Father has given to us, that we should be called children of God. And that is what we are!" .

Furthermore, spiritual adoption fosters a sense of community and unity among believers, as they are all members of the same spiritual family. This unity transcends ethnic, social, and cultural barriers, as all are one in Christ Jesus (Galatians 3:28).

Conclusion
While this entry does not include a conclusion, it is evident that spiritual adoption is a transformative and foundational doctrine within Christianity, offering believers a new identity, relationship, and hope in Christ.