Have you ever seen an ecological food chain? Have you ever really seen it, like a tangible object that you can point to, pick up and say “Look, here it is..?” Of course not. So a food chain does not exist. But biological science has made it clear that a food chain does exist. But it only exists as an invisible connection between objects in the visible concrete world. So the food chain does exist and does not exist at the same time.
The food chain is a concept. And that is what a concept is. It is the mind seeing meaning in things. That meaning can often not be found as an object in the world. Yet the meaning can exist as a relation or connection in the world. That is also what it means to understand. Understanding shows an awareness of a certain reality or (invisible) relationship. Although the relationship is invisible, it does express itself all the time.
There are different levels of abstraction we can use for concepts. The concept of a stone is a low level abstraction because it corresponds to an object which we can see, feel and measure. The concept of a food chain is a higher level abstraction, because it is itself invisible in the world of objects and only exists as a thing in the abstract realm of the mind. But we still can proof its existence objectively.
God is the highest abstraction. If you want to measure, proof, see, point to, or touch God, then God does not exist. But God does exist as the awareness of the oneness, connectedness and therefore inherent meaning of all things. It is the meaning of life. But there is no particular meaning to life. So God exists and does not exist at the same time.
That is why people who are in search of the fundamental meaning of life are actually in search of God. That is where science and religion meet. And that is why they cannot find God in an objective way in science and why there is no objective measure for the mystical experience. Because God lives in the mind as the awareness of the oneness and therefore meaning of all things. And God lives in the heart as the feeling of connectedness with all things.