It is great that a child will be cared for. It is exciting that a family will grow in depth and breadth. Those things are blessings and workings of God's grace. Yet, those things pale in comparison to the reason that adoption exists. Adoption exists to be the most real display of the gospel of Christ. That is a bold statement; and it can be taken lightly, but shouldn't be. (Note: I did not say it is the greatest display of love; that would be laying down one's life for another [John 15:13]; though that is not necessarily void in adoption.)
Here are some implications of the statement "adoption exists to be the most real display of the gospel of Christ." That implies that orphans exist for the glory of God. That implies that parents that suffer greatly because of the difficulties that are unique to parenting adopted children are for the glory of God. That means that poverty is for the glory of God. That means that suffering is for the glory of God. Even though God is absolutely saddened that there are orphans and poverty and unique sufferings, He sovereignly has them exist for the glory of his name. Is God cruel? By no means. Here's why.
If the Lord is the ultimate and the most satisfying, then the best thing He can give us is himself. Problem: we were all children of wrath (Ephesians 2:3), not children of God. So, the best thing that we could have (God) is not what we had (God's wrath). How then could we be transferred into the family of God? Adoption.
How did that adoption happen? The Word became flesh (Jesus Christ) in order to live and fulfill the covenant established on Mount Sinai as the true Israel and to die and fulfill the covenant established with Abraham as the one who was obligated to fulfill the covenant. So then, we became heirs. But heirs with no benefit until we would die to lay hold of our estate (the kingdom of God). So, Christ was raised from the dead, ascended to the right hand of the Father, and sent his Spirit in and among all who would believe (John 1:12-13) such glorious news to not leave us as orphans (John 14:15-27).
We were adopted from the domain of darkness, of sin and into the kingdom of light, of holiness, of righteousness. We were once sons of wrath and of the "prince of the power of the air" (Ephesians 2:2), but now we are sons of the Most High God, Yahweh himself!
Reality: even though we have been adopted, we still struggle with identifying ourselves as children of God, and so we sin. Yet, He reminds us over and over and over that we are his and He is ours; and He graciously restores us, disciplines us, and gives us great delight and joy in him.
He, Christ, left his home for certain death to bring children into his family.
As we leave our home, we may not be going for certain death, but we are definitely going to die (to sin and self). We go to bring an orphan into our family that he may no longer be an orphan but rather a son. There will be times when he will think, feel, and act like an orphan and not "like a Svaleson"; but we will be there to graciously restore him, discipline him, and give him delight in belonging to our family (Lord willing :-). Oh, there is so much more grandeur to show!
(Let me make a quick note. We cannot draw every parallel. We are not rescuing a child from a lesser culture and area; Christ did that for us, but we are not doing that in this case. The United States isn't any better than other cultures.)
And all of this is done to display the glory of God in Christ Jesus. This is done to make disciples of Jesus who make disciples of Jesus. This is done because we want to make Christ's name the greatest, because his name is the greatest. Adoption exists to be the most real display of the gospel of Christ. And we are excited to be a living, breathing, walking testimony to that reality.