It's tempting to think we've reached the bottom here: matter is mostly empty space, solidity is electromagnetic force, the parts are particles. A clean, finished picture. But go one level deeper, into the nucleus itself, and the ground shifts under the very idea of "stuff."
Nearly all of your body's mass lives in the protons and neutrons of your atomic nuclei. So you'd assume your mass is the mass of the particles inside them — the quarks. It isn't. The quarks themselves account for only about one percent of a proton's mass. The other ~99% is binding energy — the energy of the strong force, carried by gluons, raging inside the proton to hold the quarks together. By Einstein's E=mc², that energy is mass. Read the consequence slowly: roughly 99% of your physical mass is not matter at all. It's the energy of a force doing the work of holding you together. You are, almost entirely, binding. And we are nowhere near the bottom of understanding it. The "proton spin crisis" — the still-unsolved puzzle of how the proton's spin is actually built from its churning interior — has been open since the 1980s. Even the proton's radius threw physics into a years-long crisis (the "proton radius puzzle") when two methods of measuring it disagreed, only recently easing. The thing that constitutes almost all of you is, on close inspection, less a solid object than a sustained event — a storm of force we can measure exquisitely and still cannot fully explain.
"He existed before anything else, and he holds all creation together." Paul wrote that of Christ centuries before anyone could have known how startlingly literal it would become. The verb — holds together, sustains, in Greek synistēmi — turns out to describe the deepest physical fact about you: that you are constituted, at rock bottom, not of independent stuff but of a holding-together, a binding that is most of your very mass. Pull the binding and there is almost nothing left. We reach for God as the one who keeps us "together" and assume we're speaking in metaphor. The physics says the metaphor was an understatement. You are made, in your foundations, of being-held.
There is a quiet terror that can come in the adult middle of things — the fear that if you ever stopped striving, stopped gripping, the whole construction of your life would simply fly apart, because underneath it there's nothing holding it but you. The proton answers that fear at the level of physics. What holds you together was never your stuff and never your effort; it is a binding that constitutes you, that is most of you, and that you contribute nothing to maintaining. And the One in whom "all creation holds together" did not stay at a safe, sustaining distance. He stepped into the matter He binds, was Himself broken, and holds you still. You are not a fragile collection one bad day from scattering. You are, all the way down, something held — by a force you can measure, and a God you can trust.