How do we know adoption is true in a Christian context?

The doctrine of adoption teaches that God ordained the adoption of believers before the world was created, and this act is vital for understanding our relationship with God. Spurgeon highlights that, although adoption was established in eternity, its effects manifest in time when believers transition from a state of nature to grace. This implies that while adoption is an eternal decree, its realization is experienced personally through faith, as individuals accept Christ and enter into their inheritance as children of God.