God is a foundational assumption that must be in place to have an intelligible view of the universe. It’s not that unbelievers don’t think intelligently about the universe, but their most basic assumptions about it are hostile to the way they engage the world around them. Without God, morality becomes impossible to justify. As do scientific laws, and laws of logic. These have to be designed by Someone and deliberately set within our universe, or we have every reason to doubt their existence, or at least wonder if they actually mean what we have always assumed them to mean. Honest unbelief requires contemplating the possibility that we might just be lying to ourselves about what the universe is, and what we are.
“The fundamental word is “revelation.” Derived from a Latin noun meaning “unveiling,” it indicates that God has taken the initiative to make himself known. The reasonableness of this concept should be plain. For whoever or whatever God may be, he is altogether beyond our knowledge. “Can you fathom the mysteries of God? Can you probe the limits of the Almighty?” (Job. 11:7). Indeed not. His infinite greatness is veiled from our eyes. We cannot discover him by ourselves. If we are ever to know him, he must make himself known.” -John Stott, Understanding the Bible