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.
***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. ***
Then you would assume wrong. A divorce from adoptive parents, while unusual, can still occur at the request of the adoptive child for any reason, or none given, once they (depends on jurisdiction) approach or surpass the age of majority.