Having no body, form, or substance is the metaphysical, the nature of our reality in an abstract sense. Metaphysics is the philosophy of the nature of the world. Coming from forces beyond our natural world, metaphysics may not be concretely or scientifically proved. Yet many will attest to it’s existence. It is part of the belief system, but where does it come from? We can put faith in the experiences of others, leaving us to wish for much of the same.
Things exist because we are conscious of them. That alone proves their existence, if only to the entity cognitive of their existence. The main focus of human knowledge is causality. For every action, there is an equal and opposite reaction. You don’t have to be an Einstein to figure that one out. Some believe, as is written in ancient texts, that cause is the effect concealed, and effect is the cause revealed. I can see how this plays out in basic day to day human relations, a basis for interactions with our fellow human beings.