How is the Bar Mitzvah different from Roman and Greek adoption?
The Bar Mitzvah is the Hebrew counterpart, occurring when a boy reaches 14, but it is not the same category as Roman and Greek adoption. Those adoptions were secular, preparing a child through tutoring to become a co-worker in the family business, whereas Paul's adoption places believers immediately as heirs.
Les explains that the Bar Mitzvah is the Hebrew equivalent, occurring when a boy reaches age 14. However, it is not on the same category as Roman and Greek adoption because those were in the secular world and were preparing their child to come in and be a co-worker in the business. By contrast, Paul teaches that the moment we become a believer, we do not go through years of tutoring and training; we are immediately placed as an heir with the Father and the Son. He says we were predestinated not to heaven or hell, but as a believer to that position with Christ from day one, as a joint heir. If we are a joint heir, the other parties' inheritance becomes ours.