***We are adopted into His family. That can be rescinded.
Not by a Christian or a Christian God it can’t. When one adopts, one is making a commitment. If you made the commitment to adopt a child, would it ever be the Christian thing to do to “unadopt” that child? The child might turn out to be very troublesome, but it would take an act on your part to give up (to quit), and rescind the adoption. (The child doesn’t get a say once it’s done.) I don’t see how a Christian could do that. I don’t think our God would do that either.***
I appreciate your last statement.
However, you are wrong about the child not being able to rescind his/her adoption. The child can petition for it to be rescinded.
Now, it wouldn’t be nice to reject a good parent, or a good God, but not all people are nice.
I'm actually not all that familiar with this area of the law, but I would strongly think that any such request would have to have grounds. That is, there would have to be a showing of parental unfitness. My children could not "divorce" themselves from my custody "just because". I would assume it works the same in the case of legal adoption. Since God is incapable of unfitness, the turn your analogy takes would not apply.