Chronological time

1. Readers might find my title redundant. What other kind of time is there? Isn't time necessarily chronological? Depends on what you mean. 

Let's distinguish between chronological time and biological time (or physical time). According to Christian eschatology, God will rejuvenate believers at the resurrection of the just. The saints will have youthful, ageless bodies. 

Let's say the optimal age of a human body is 20. Strictly speaking, I'm not sure the human body has an optimal age. From what I've read, different body organs and systems mature and age at somewhat different rates. In glorification, the optimal age would have to synchronize these rates. For convenience, let's stimulate age 20.

So an immortal saint could be a billion years old, but have the body of a 20-year-old. Chronologically he's a billion years old, but biologically he's only twenty years old. Biologically, he stays the same age while chronologically he continues to age indefinitely. 

2. That parallels a distinction drawn by Philip Henry Gosse. Normally, physical and chronological time coincide, but Gosse had the insight to appreciate that, in principle and possibly in practice, these can be split apart. It's a profound insight, equal to McTaggart's distinction between the A-series and the B-series. The difference is that McTaggart is hailed as a great philosopher of time because he was an atheist, whereas Gosse is mocked because he was a creationist who devised and utilized his distinction to rescue traditional creationism. 

3. Finally, this involves a limitation on divine omnipotence. God can create a father who is biologically younger than his son, but God can't create a father who is chronologically younger than his son. For instance, God could rejuvenate Abraham, but refrain from rejuvenating Isaac. If so, Abraham would be biologically younger than his own son.

However, even an omnipotent agent can't make Abraham chronologically younger than Isaac because chronological time requires relative chronology. A father, to be a father, must preexist his son. It's a cause/effect relation, and the direction of causality, like time's arrow, is linear. 

I'd add that it's useful to recognize certain limitations on divine omnipotence because that's an important consideration in theodicy. There are some things even God can't do.