When physicists talk about a Theory of Everything, they basically mean a theory that accounts for both general relativity and quantum mechanics.
Some people, though, want a Theory of Everything that accounts for both general relativity and the Atonement. This is basically what I mean by "theophysics."
The desire for theophysics seems to come from two directions. In my experience, most who have it seem to lack faith in faith; they have a science-shaped hole in their Christian faith.
But there are also those who have an excess of faith in science. They find a science-shaped bung, so to speak, like an extra piece in a jigsaw puzzle, that they want to use to patch up or at least reinforce their faith.
In both cases, people fail to realize that physics and theology are not directly related sciences. Neither is a special case of the other. As the blessed John Paul II wrote, "Faith and reason are like two wings on which the human spirit rises to the contemplation of truth." Rising on two wings is challenge enough; if faith really were a subset of reason, if there were really only a single wing, the human spirit would never get off the ground.
Now, the differences between faith and reason have been recognized for a long time. How they can be unified is just Aquinas 101 -- or, technically, I,1,i:
Sciences are differentiated according to the various means through which knowledge is obtained... Hence theology included in sacred doctrine differs in kind from that theology which is part of philosophy.
But this is a unity of complementarity, not (as with a Theory of Everything) a unity of identity. And it's a complementarity between theology (as included in sacra doctrina) and philosophy, whereas theophysicists want an identity between theology and physics.
The problem is that "no science deals with individual facts," and Christianity deals with nothing if not with the individual facts of the incarnation, death, and resurrection of Jesus Christ. Contrary to the claim of Frank J. Tipler, Christianity is not -- it flat can't be -- "a branch of physics."
On the other hand, plenty of the people with science-shaped holes in their faith seem more than ready to dispose of the individual facts of Christianity. It is within their power to do so, but the resulting theophysics will at best be only accidentally compatible with faith in Christ.
So, whether you start with theology or you start with physics, if you wind up at theophysics you've gone in the wrong direction.