Scripture commands all Christians to love, forgive and welcome others, but it does not command all Christians to adopt. As a matter of fact, it doesn’t even require that some Christians adopt.
What we can say with absolutely certainty, though, is that God the Father does expect those whom He adopts to visit orphans in their affliction (James 1:27, “Religion that is pure and undefiled before God, the Father, is this: to visit orphans…”). My point is simply this: the Love that adopted us becomes a love in us that cares for orphans. As Christians, we should be moved and empowered to visit the fatherless because God himself visited us when we were without hope in this world (Ephesians 2:11-13). For some, this visiting will mean adoption; for others, it may involve helping others adopt or joining with other Christians to provide some form of humanitarian aide or support for orphaned and vulnerable children.
However we Christians are involved in visiting orphans in their affliction, it should be Christianity’s vertical to horizontal movement that moves us out in compassion. Christians should not only be the most loving, forgiving and welcoming people on the planet, we should also be the most orphan-caring.