What is God ?
In algebra, we denote the unknown quantity by a simple letter x. Then we can subject x to all sorts of manipulations and transformations, before even knowing value of x.
Similarly if we want explanations for observed phenomena, and are unable to provide any plausible theory, well, call it x ( GOD ).
In Youjo Senki by Carlo Zen when Tanya von Degurechaff refuses to acknowledge the cruel being playing with her life as god she declines to refer to him/her /it as anything but Being X much to the "god"'s vexation.