Theistic philosophy sees God as a creator. Creation as a god cannot come from a material source so this creator is often given the property to create by thought. Much how our imagination is limited, God is not, and everything we see is in fact a thought of God. Humans have a limited capacity to share in this. These philosophies often see our roll, not as creators of the universe, but those who observe it. Being is generated by god but our capacity is a diminutive form of it. Instead of creating being we recognize it and name it.
Naming can almost seem a form of creation. If we name something few have experienced or few can understand we are credited for this naming. This naming still has the abstract quality of being and all its vagueness. Our names are generalities that can be applied over and over again to different observations. We take this practice when we name our children names that have named countless other people. However, names that are oddly specific or names of well known people strike us as odd. So odd we wonder if their parents are not capable of thinking clearly. Here it is clear that naming is important to allow multiplicity and avoid being overly specific.
Mathematical naming is an extreme example as an exception to our naming schema. In logical practices like these it's import that a name cannot denote anything other than the very thing at hand. In mathematical formulas its important that a symbol mean something specific and not allow the vagueness words bring in such as different understandings of what a word means. An equation cannot be calculated if this is not the case.
Reason involves the matching of our understanding with what is created around us. We attach words to these understandings but if we become too descriptive we lose the pairing of our understanding towards reason. For instance, it's common for someone grappling with a concept to expect a knower of this concept to relate it in a clearly assembled set of words--in much the same way as a succinct formula. This is rarely a possibility and rejecting this simplicity is often the first step in learning. This succinct, precise language can be bound by logic but it does not amount to Reason.
To come back to the point of theism, we should recognize that Reason would be us adjusting our understanding to God's thoughts. The question is does Reason have currency in atheistic philosophy. Here being does not have a starting point that is outside our self. Descartes does give god the credit of a creator but he does launch a train of thought that could go in another direction. His famous "I think therefore I am" does amount to giving our thought as a generative power much like God. His rationalism give our source of thinking first before we can then intuit any concept of God.
Other stand-ins for God include society and further yet the individual. This wraps up philosophy in the terms of politics and our will. Particularly the existentialists took hold of this and promoted the individual as the locus of being and creating being but curiously preoccupied with nihilism.
As philosophies move away from theistic foundations the source of being becomes less important. The role of language can even mock this non-significance. The vagueness in words can suggest a multiplicity that lacks intelligibility. Word play can be a spectacle about our distinct inability to know Reason in any meaningful way. There is no grand thinker causing the being around us in this case. The words we use to correspond with Reason are empty.