I have not forgotten about going through the book, but I can't seem to find it so, until I do, there's more to think about and consider on the topic of adoption by God.
Here's some quotes by some men who have thoughts on the adoption of sinners by God:
If you want to judge how well a person understands Christianity, find out how much he makes of the thought of being God’s child, and having God as his Father. If this is not the thought that prompts and controls his worship and prayers and his whole outlook on life, it means that he does not understand Christianity very well at all... JI Packer, Knowing God.
It is indeed a great thing to be right with God the Judge through the person and work of Jesus Christ. It is a great thing to be forgiven of sin, to be free from the fear of God’s wrath. But it is possible to grasp these great realities and remain unaware of what is even greater: we are adopted and loved by God the Father. In Christ, God the Father justifies us, but he does not stop there: he adopts us as his sons. CJ Mahaney, For the Fame of God’s Name: Essays in Honor of John Piper.