Liz cried for joy when she and her husband received the birth certificate and passport for their child, making the adoption legally binding. Now Milena would always be their daughter, forever part of their family. As she pondered the legal process, she also thought of the “true exchange” that happens when we become part of Jesus’s family: “No longer are we held down by our birthright of sin and brokenness.” Rather, she continued, we enter into the fullness of God’s kingdom legally when we are adopted as His children.

In the apostle Paul’s day, if a Roman family adopted a son,…