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.