"He is the image of the invisible God, the firstborn of all creation. For in him were created all things in heaven and on earth, the visible and the invisible, whether thrones or dominions or principalities or powers; all things were created through him and for him. He is before all things, and in him all things hold together. He is the head of the body, the church. He is the beginning, the firstborn from the dead, that in all things he himself might be preeminent. For in him all the fullness was pleased to dwell, and through him to reconcile all things for him, making peace by the blood of his cross (through him), whether those on earth or those in heaven.
"And you who once were alienated and hostile in mind because of evil deeds he has now reconciled in his fleshly body through his death, to present you holy, without blemish, and irreproachable before him, provided that you persevere in the faith, firmly grounded, stable, and not shifting from the hope of the gospel that you heard, which has been preached to every creature under heaven, of which I, Paul, am a minister.
"Now I rejoice in my sufferings for your sake, and in my flesh I am filling up what is lacking in the afflictions of Christ on behalf of his body, which is the church, of which I am a minister in accordance with God's stewardship given to me to bring to completion for you the word of God, the mystery hidden from ages and from generations past. But now it has been manifested to his holy ones, to whom God chose to make known the riches of the glory of this mystery among the Gentiles; it is Christ in you, the hope for glory. It is he whom we proclaim, admonishing everyone and teaching everyone with all wisdom, that we may present everyone perfect in Christ.
For this I labor and struggle, in accord with the exercise of his power working within me" (Col. 1,9-29).
The answer to the question what, or, more accurately, who, holds all things together is Christ. How all things are held together (in Christ) is a scientific question. It is by scientifically seeking the answer that we begin to attain an understanding of reality that is not divorced from our experience. In other words, there are meta-physical questions and questions of physics. This seems to me a very crucial distinction that is all too often lost, not only on people like Richard Dawkins, but on people of faith as well. Our faith calls us to the space between rationalism and fideism, both of which we reject. It is necessary to understand this crucial distinction in order to shape a sound methodology as we seek a synthesis. Arriving at a synthesis enlarges our understanding, which, in turn, enables us to follow the One in whom, by whom, and for whom all things hold together. I am quite certain that this is a valid inference to draw from what St. Paul has written.
In his great synthesis, the Summa Theologica, St. Thomas of Aquinas, the Angelic Doctor, in objection three, to question two, of article one, in the first part observes: "Further, the existence of truth is self-evident. For whoever denies the existence of truth grants that truth does not exist: and, if truth does not exist, then the proposition "Truth does not exist" is true: and if there is anything true, there must be truth. But God is truth itself: 'I am the way, the truth, and the life' (John 14:6). Therefore 'God exists' is self-evident." He concludes: "The existence of truth in general is self-evident but the existence of a Primal Truth is not self-evident to us." Rather, as the apostle tells us, "For in him all the fullness was pleased to dwell, and through him to reconcile all things for him, making peace by the blood of his cross (through him), whether those on earth or those in heaven."