Is death a form of existence? If the opposite of existence is non-existence, then the opposite of to exist is not to exist. Even for the scientist who does not believe in the afterlife, there is a belief in matter. A person, who dies, does not cease to exist. At the very least, their corpse simply changes its form. So, whether in life or death, we exist (though perhaps not consciously).
I don’t think it is possible to conceive of non-existence. Every aspect of the thinking process engages contradiction. I question at what point birth becomes existence. There is something here that I cannot fathom. Does birth (in the early stages of the womb), itself, produce existence? I cannot think so. Existence precedes birth. I don’t think I can marshal an argument for this point, yet. So I only hold the proposition tentatively. But one point, at least, seems clear: The greatest miracle is not resurrection, it is coming into being.