Neither the theist nor the atheist understand what a mystic is even saying.
It is not so much that they disagree, but they usually cannot even hear what is being said.
Most theists believe in a divine being and consider all those who don’t believe to be atheists.
Most atheists disbelieve in a divine being and assume all who are religious must believe in some such supernatural being by definition.
But mystics are not speaking about a being. We are speaking of being per se.
We do not greet the morning sun as a created object, nor as an inert fact, but as a revelation of the invisible unthinkable energies of our universe. We greet every life form not as a soul, nor as a carbon chain reaction, but as something more. To us, that “something more” is not a projection of human purposes upon an indifferent universe. Life, too, is a revelation of the profound nature of it all.
We are at one with every religion that remembers “God” is a symbol of something beyond any religion. We are also at one with the atheistic scientist looks through a telescope and mutters , “wow!” To us, every such evocation of wonderment is an expression of the divine name; and every religious hymn or prayer that does not move us to silent wonder is a profaning of that same name.
A mystic’s religion does not reside in credulity but in reverence. For us, the three letters g-o-d are optional. We do not believe or disbelieve in our symbols. We sing a hymn to the universe with our very lives because we know that we too are its revelations.