What is it that marks each of us as the same individual at birth, as an adult, and in the resurrection? The adult is the same person as the child, despite all the change that goes on within the human body. Similarly, despite the transformation that will occur at resurrection, we know from Paul that we will still be the same person.237 Millard Erickson, Christian Theology This issue [whether people will be resurrected at the age they died] caused the spilling of much theological ink, especially during the Middle Ages. . . . By the late thirteenth century, the church’s emerging consensus was this: “As each person reaches their peak of perfection around the age of 30, they will be resurrected, as they would have appeared at that time—even if they never lived to reach that age.” Peter Lombard’s discussion of the matter is typical of his age: “A boy who dies immediately after being born will be resurrected in that form which he would have had if he had lived to the age of thirty.” The New Jerusalem will thus be populated by men and women as they would appear at the age of 30 . . . but with every blemish removed.
~ Alister McGrath