"So, no matter what your field of study is, it is based on God, and it is about God. It says something about God, and God says something about it. Your job, as a Christian who is in your particular field, is to find out what these "something"s are so that you may love God more perfectly."
Now, I hope nobody expects me to say things like "since the first energy level hydrogen is at 13.6eV, it means that God wants us to tithe from our gross income instead of our net income". That's silly. The universe is one of God's creations, and physics is a particular filter that we use to look at that creation. We don't expect decisions on specific theological issues via physics, no more than we expect a painting to contain the artist's phone number, or a film to contain the director's tax returns. Rather, we expect that physics will tell us about God in broad strokes. Nevertheless, these will be deep truths about God, just as a great work of art ably expresses the artist's deep thoughts and feelings.
Also, this post will not be an "if physics, then God" kind of "proof" that some may expect. I will write things of that flavor in the future (which still won't be "proofs"), but this post is not it. You cannot prove the existence of God that way. Instead I will postulate that he already exists, then explore of what physics says about God and show that physics is compatible with the Christian God.
So, to begin: the first thing that many people note about physics is its mathematical logic and consistency. The laws of nature are mathematical in nature, and they are consistently applied in the universe. It reveals a creator who has those traits as an important part of his personality - God is logical and faithful.
There is an austere beauty about the laws of physics; they expresses the kind of unyielding truth that remains true whether you believe in it or not. These laws are applied consistently whether you're inconvenienced by them or not. And yet, the knowledge of these laws illuminates your mind, and your very life depends on the consistency of their application. There is something like the fear of God in studying and approaching them - in looking at something that is larger than yourself, immovable and implacable and inviolable, and yet is also your light and life.
In light of the above, one of the strangest things about physics is that it's comprehensible and interesting. On the one hand, the universe is not fundamentally too hard or strange to understand - we humans, with our 1500cc of cranial capacity, can somehow make sense of even things like quantum mechanics without quite going mad from the revelation. On the other hand, it is not so simple as to be boring: if the only important thing about the universe was that it's logical and consistent, then total nothingness would be the simplest thing. But we are at neither extreme, and physics is fascinating and fun. I cannot shake the feeling that physics was set as a puzzle for us to solve. It seems that God has conspired to tie our capacity for thought to the very mechanics of the universe that we think about, by making our physical brains the engines for thinking. This ensures that the puzzle will be challenging but not impossible.
There are also a great deal of unexpected, creative surprises in this puzzle we call physics. Again, this is not something you'd expect from something described as "logical" and "consistent". Yet progress in science takes us to unforeseen and exciting new directions at every turn. Who, before physics, imagined the periodic table emerging from spherically symmetric solutions to Schrodinger's equation? Who foresaw the unification of electricity, magnetism and relativity in the Lorentz-invariant form of Maxwell's equations? These are a testament to the artistry of the Great Architect, who infused creativity into a logical, consistent universe.
The laws of physics are said to be elegant, by which physicists mean that many phenomena are explained by only a few simple laws; This is true enough, but the simplicity of the laws are... complicated. It seems to me that the simplicity in the number of laws comes at the expense of complexity in the mathematical structures necessary to express these laws. So we say that quantum mechanical wavefunctions live in an infinite-dimensional Hilbert space, giving us the simple and elegant Schrodinger equation, but we somehow forget to mention to non-physicists that to make an infinite-dimensional Hilbert space, we need to pile several infinite things on top of each other in very specific ways (math exercise: construct an infinite-dimensional Hilbert space starting from whole numbers). This is why most people can't do high-level physics, despite the equations being "simple". This is how physicists end up saying black holes have no hair, (by which they mean that a black hole is a simple object - you only need three numbers to describe them completely) while the average person can't understand a single letter in Einstein's field equations. But to those who understand them, these laws of nature are simple and elegant and beautiful.
Now, what does this "elegance" say about God? If these physical laws reflect God's character, it suggests that God himself must be like them - somehow simple but complex. Thomas Aquinas has expressed that God is infinitely simple, and therefore appears as infinitely complex to finite minds. I feel that this statement agrees well with the characteristics of the physical laws of the universe that God created.
Physics also shows that the universe itself is not the final, "ultimate being" which exists independent of other things: the material universe depends on physical laws, and physical laws depend on mathematics. That which we call an electron need not necessarily exist, but if one does exist, it needs to obey the physical laws, which are not themselves an electron. In turn, the physical laws are mathematical in nature, but they are not themselves just pure math, for not all mathematical statements are physical laws. At each step these show that they are not the ultimate reality, since they depend on something else for their existence, yet are not the thing that they depend on. All these things are contingent upon Someone who truly is the "Ultimate Being" to make them the way they are.
Speaking of electrons - I love electrons. They are elementary particles (as far as we know), which are familiar to middle school students ("they're the negatively charged particles in atoms!"), yet causes Nobel Prize winners to bang their heads against the wall ("how to derive the rest mass of an electron?"). They show that even the smallest things contain the infinity and mystery of God. Thinking about electrons is both humbling and uplifting, for anything created by God - no matter how small - cannot truly be understood apart from him, yet we can get a glimpse of God's character by looking at that small creation. In light of all this, I'd like to quote Thomas Aquinas again, this time to update him: he's said that "all the efforts of the human mind cannot exhaust the essence of a single fly". It should now read, "all the efforts of the human mind cannot exhaust the essence of a single electron".
Also, the process of studying physics shows that there is more to this existence than studying physics. You won't hear many physicists say it professionally, but in private some of them admit that there are better things in life than to do physics (no, I'm not just saying that. I have firsthand accounts). There is a limit to calculations for macroscopic objects from physical first principles, which seems insurmountable in the foreseeable future. Even if we could solve for the wavefunction of some macroscopic object, such as an apple, it'd be totally useless because we could never write down the answer (it'd be too long), nor would we be able to interpret it by wading through the solution. As interesting as physics is, its most interesting function is to serve as the substrate for the other, higher order organizing principles which arise out of it. And to discover those, we have to go on up to other fields, such as chemistry and biology. Those are what will tell you that the apple is delicious. But even those aren't the last word on what's truly important in life.
All of these higher order organizations flow out of physics. Like a well-crafted video game, the entire play experience stems naturally from the fundamental mechanics of the game, instead of having to be added ad-hoc at different times. The manifold wisdom of God is revealed in that when we pursue life's highest goal - to glorify God and enjoy him forever - we do so through the natural extension of the ordinary workings of physics through the higher levels of organization. This is God's perfect craftsmanship: that all these levels of understanding the universe - all the different filters we use to look at creation - work perfectly, consistently, and in unison to generate the universe that God wanted to create. Thus they all testify to his workmanship, and point to him as the one thing that this existence is for and about.
In the next post of this series, I'll address the other half of our question: What does God say about physics?
You may next want to read:
How physics fits within Christianity (part 2) (Next post of this series)
How is God related to all other fields of study?
Science as evidence for Christianity against atheism (introduction)
Another post, from the table of contents