"God... a being whose only definition is that he is beyond man's power to conceive"

This quote by Ayn Rand speaks to the strange and also unknowable nature of God. It recommends that God is past the scope of human understanding, and that any kind of effort to specify or understand God is futile. This is because God is up until now past the limits of human expertise and experience that it is difficult to fully comprehend or explain. The quote implies that God is an idea that is beyond the ability of the human mind to understand, which any kind of effort to do so is useless. This is a suggestion that, while we may trust God, we can never absolutely understand the divine. It is a tip that, while we might have faith in God, we have to accept that there are some things that are merely past our understanding.