Let us therefore strive to enter that rest, that no one fall by the same sort of disobedience. For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and spirit, of joints and marrow, and discerning the thoughts and intentions of the heart. And before him no creature is hidden, but all are open and laid bare to the eyes of him with whom we have to do. Hebrews 4:11–13 (RSV)
'For I do not seek to understand in order to believe but I believe in order to understand' St. Anselm 1033-1109
I don't pretend to comprehend the physics used to explain how the universe came into being. Most scientists agree that a massive explosion took place about fourteen billion years ago, and the universe began. It is called the 'Big Bang' theory.
Genesis touches on this where it witnesses to what God did in the beginning. God spoke, and things came into being. I don't pretend to understand how this is possible either.
Fortunately for all things, the universe's existence does not require my comprehension for it to be. God's Word is indeed active, doing far more than human minds can grasp.
The Word not only calls all things into being, but the Word becomes flesh and lives among us. Jesus is the Word who bears the redemption of the cosmos He created.
St. Anselm is correct. Understanding is not the key to faith. Faith is the key to understanding. At least as much understanding of God as we can know. I remind myself of this frequently lest I get too hung up on trying to understand God before I may trust Him.