We have all noticed it: the extreme ends of any spectrum tends to look strangely alike.
And so it is with atheism and mysticism as well, and materialism and a nondual view.
Atheism and materialism say: it is all one, it is all matter.
Mysticism and a nondual view say: yes, it is all one, it is all God, it is all Spirit, it is all emptiness and form.
Atheism and materialism (may) say: the universe is a clockwork, cause and effect, everything is determined, we are biological machines with no free will.
Mysticism and a nondual view say: the whole realm of form and phenomena is a seamless fluid whole, and when it is filtered into parts, it is all cause and effect. In fact, for any change in any aspect of this whole, there is infinite causes and infinite effects, and so it is also for our human self.
Our human self is a puppet with a million strings attached to it. Every choice, every action, has infinite causes stretching back to the beginning of time and out to the extent of the universe. It lives its own life. There is doing, but no doer. There is choosing, but no chooser.
It is all Ground appearing as clear awakeness and the infinitely varied world of phenomena, as seeing and seen, as form of emptiness, and emptiness dancing. There is only one I, and that is Spirit. Choice? Who needs it?
Atheism and materialism say: there is no meaning inherent in life or the universe. We have to create our own meaning.
Mysticism and a nondual view say: there is no meaning inherent in Ground, it is free from meaning as it is free from any characteristic. Meaning only arises in the world of form and phenomena, it only arises in our human life. We create our own meaning. And any meaning is only a relative truth, there is nothing absolute or final in it.