I'd like to consider some potential objections to the Christian doctrine of the final state, then consider how to field those objections.
Generally stated, are there aspects of the final state that are naturally impossible? There are things that even an omnipotent God can't naturally do. That doesn't mean he can't do them; just that he can't naturally do them. God would have to circumvent natural processes to make it happen.
Let's take one example: Is biological immortality naturally possible? I don't think we know the answer to that as of yet. To my knowledge, scientists haven't figured out why humans (and other organisms) age. Yet the Bible promises that we will have immortal bodies.
One question is whether aging is caused by a master switch. Is there one mechanism that triggers a cascade effect. Assuming that's the case, then if that switch were improved, renewed, or replaced, the organism wouldn't age. The human body already has some capacity to regenerate itself. Just not systematically and permanently.
Perhaps, though, there is no single mechanism of senescence. Perhaps organs and body parts individually age, independent of each other. The whole body wears out, and there's no discrete solution.
In that event, how would God preserve the body from aging? The answer depends in part on whether senescence is naturally inevitable. If so, then God must supernaturally preserve the body.
How might God do so? Of course, the answer is speculative, but let's speculate. We might begin by asking what's a body? A body is a specific organization of matter. Of atoms and molecules, in various combinations, combinations in various scales of magnitude. Highly structured patterns of particles and fields of energy. If aging means organs and body parts lose the structural pattern necessary to function, God could repair that by bringing the atoms and molecules back into alignment.
Another possibility is replacement. God replaces aging parts, organs, body systems. In principle, God could instantly replace the entire body with a duplicate body.
Suppose aging is naturally inevitable. Suppose your physical prime is between 18-28. Suppose every ten years, God gives you a brand-new, 18-year-old body. God replicates the pattern of atoms and molecules that compose your body.
That isn't pure speculation. After all, how is the resurrection of the body going to occur? In many cases, there is no extant corpse to work from. Our bodies disintegrated. The body would need to be recreated from scratch. The way to resurrect our bodies is for God to replicate the specific organization of matter that constituted our distinctive bodies. At least, that's my preferred explanation.
Let's consider another potential objection. The sun will exhaust its fuel. Moreover, to sustain life on earth, the sun must maintain a very specific output. Long before the sun is a spent force, its output will be at the wrong level to sustain life on earth, which has very narrow, very exacting parameters.
Moreover, the problem isn't confined to the sun. There's the distant specter of cosmic heat death. Stars have natural lifecycles.
Once again, we might evoke the replacement model. God instantly replaces an aging sun with a new sun the right age to sustain life on earth.
Here's another potential objection:
Large moon with right planetary rotation period (which stabilizes a planet’s tilt and contributes to tides). In the case of the Earth, the gravitational pull of its moon stabilizes the angle of its axis at a nearly constant 23.5 degrees. This ensures relatively temperate seasonal changes, and the only climate in the solar system mild enough to sustain complex living organisms.
A few, large Jupiter-mass planetary neighbors in large circular orbits (which protects the habitable zone from too many comet bombardments). If the Earth were not protected by the gravitational pulls of Jupiter and Saturn, it would be far more susceptible to collisions with devastating comets that would cause mass extinctions. As it is, the larger planets in our solar system provide significant protection to the Earth from the most dangerous comets.
Problem is that over time the relative position of planets and satellites in the solar system changes. For instance, due to tidal friction, the moon is moving incrementally away from the earth. A solution would be for God to restore the configuration necessary to maintain life on earth.
Now let's consider an objection from Leibniz:
Newton and his followers also have a very odd opinion regarding God’s workmanship. According to them, God’s watch—the universe—would stop working if he didn’t rewind it from time to time! He didn’t have enough foresight to give it perpetual motion. This machine that he has made is so imperfect that from time to time he has to clean it by a miraculous intervention, and even has to mend it, as a clockmaker mends his work.
The oftener a clockmaker has to adjust his machine and set it right, the clumsier he must be as a clockmaker! In my view, the world always contains the same amount of force and energy, which changes only by passing from one material thing to another in accordance with the laws of nature and the beautiful order that God has preestablished. And I hold that when God works miracles, he does it not to meet the needs of nature but to meet the needs of grace. Anyone who thinks differently must have a very mean notion of the wisdom and power of God.
A final point: If God has to mend the course of nature from time to time, he must do it either supernaturally or naturally. If supernaturally, this is appealing to miracles in order to explain natural things; and that amounts to a reductio ad absurdum of this hypothesis, for once you let in miracles anything can be ‘explained’ with no trouble at all. And if God’s mending is done naturally, then rather than being intelligentia supramundana he is included in the nature of things—i.e. is the soul of the world.
His objection has some merit. Newton postulated divine intervention to shore up gaps in his theory. That's ad hoc.
However, the Leibnizian objection is overstated. It's not a design flaw that when nature is left to take its course, stars burn out and planetary configurations shift. That's what's supposed to happen. That's the natural outcome of a natural process. The Leibnizian objection has less to do with his philosophy of miracle than his philosophy of nature. Perpetual motion is an artificial abstraction.
There's nothing intrinsically wrong with the lifecycle of stars or the realignment of planets and satellites in the solar system. (In fairness, Leibniz wasn't commenting on these specific examples). Rather, it's only a problem relative to the conditions necessary to sustain life on earth. A particular configuration of the planets and satellites isn't absolutely required, but only required for life on earth.
In addition, divine intervention needn't mean God is jumping in to make last-minute adjustments. Rather, those midcourse corrections were foreseen. They were part of God's master plan for the world all along. If God makes a world that normally operates according to second causes, but in addition, certain desirable events exceed the productive power of nature to effect their eventuation, it's not makeshift to invoke supernatural agency in such cases.
Ironically, the proposed alternative of preestablished harmony is just as ad hoc as Newton's stopgap invocation of miracles to salvage his theory. There's a difference between invoking miracles to make a scientific theory hang together, and invoking miracles to account for an outcome that isn't naturally feasible.