Imagine God as an old white-skinned man with a snow-coloured beard and a finger that sparks electricity into an inert Adam-shaped body he has just created. We appreciate, of course, that God does not ‘really’ look like that. But there we have it. In this case, after all, we are not conceptualising something that 'has' reality. We are talking (I am assured) about the ground of existence, of which we might as well say 'reality has it', or perhaps 'reality is it'. I, as atheist, cannot assert with certainty that God isn't ‘really’ this or that—because how can we be sure? But I can surely assert that he doesn’t ‘really’ look like anything I can imagine. The reason for this (the theist might say) is that to think of God in terms I can imagine gets the vector of actuality the wrong way about. It is to turn God into something that exists inside my mind, rather than that my mind exists inside God.
There’s a strong version of this line of thought, which says that it is equally heretical to conceptualise God as a cockroach, a white-skinned man with a long beard, or a superintelligent shade of the colour blue. The heresy lies not in the specific thing conceptualised, but in the action of conceptualising at all. God thinks us, we don’t think God. God ‘believes in’ us; it would be impertinent for us to ‘believe in’ God.
I have heard the expression ‘God wants us to worship Him’ deprecated on the grounds that we don’t know what God wants. The practical problem with this is that religious observation is predicated upon the notion that the things we choose to do are in some sense pleasing to God. It seems to me that the problem with a phrase such as ‘God wants us to worship Him’ is not that we don’t know what God wants, but that we are daring to imagine that God wants.