The word adoption used in the New Testament is a bad translation if you look it up in the Greek, it carries the idea of sonship or placed as a son, how can you be born of God and adopted of God, it's one of the other and there's more references to being born of God created in Christ Jesus the new creation than adoption, and even in the natural if I'm adopted by a family I may have all the rights and privileges of that family that adopted me but I still have the nature of the father that gave birth to me through procreation meaning I don't have the nature of the father that adopted me, so with God we have a new nature it's a divine nature it's the same nature that Jesus was born with which I call a nature of sonship which brings us back to Luke 3:38 Adam son of God and you cannot get that nature through adoption but through regeneration or Recreation or being Born Again of the Spirit Etc! There are very few translations that have it right but if you look at Rotherham Translation it carries the word sonship every time the word adoption is used in other translations and versions, I'm not a big fan of the NIV but it does get it right at times look it up for yourself, the Lord show me this years ago, also worth noting in this short and brief teaching is that Jesus is called the firstborn or first to be born from among the Dead meaning those who are spiritually dead in their trespasses which began at the fall of Man which is very very interesting Colossians 1:18, shalom