Those artists you refer to mistake "God, etc" for the world around us which I draw a great deal of inspiration from. Humans to me are very inspiring. It blows my mind that the universe around us was the result of natural forces and that we--also the result of natural forces--are peeling off layers of understanding of those very forces. How much mores inspiring can you get!?
inspiration is the result of complex social and biological pressures. doing art is a response to certain kinds of influence. for instance we are all molded by societies conception of what is beautiful but also by certain natural instincts that werent really intended to be considered by a conscious mind. i suppose one could say the exact nature of a given artist's inspiration isnt important. if you like doing art, do so.