There’s a lot of teaching in the New Testament about how Christians become adopted children of God (e.g. Rom 8:15, Eph 1:5). Adoption in Roman society at the time of the New Testament was different to adoption these days. It served a social function, in a similar way to an arranged marriage. ‘Suitable’ children were adopted into another family, which resulted in advancement for both the child and their birth family. And it’s the same with us and God. God has offered to adopt us as his children, so that we can benefit from his parenthood and receive an inheritance.