How do we know adoption is true?

The doctrine of adoption is rooted in the sovereign choice of God, as cited in Ephesians 1:5, which says He predestined us unto the adoption of children by Jesus Christ to Himself according to the good pleasure of His will. This passage reveals that God chooses who will be His children, and this decision exists outside of human works or merit. Believers are assured of their status as children of God through the witness of the Holy Spirit (Romans 8:16), who confirms our identity in Christ. This assurance produces a profound sense of security and belonging, knowing that we are accepted in the beloved.