Your David Hume quote reveals nothing but prejudice/bigotry. He was part of a rational/scientific movement which was in itself a philosophical position now known as physicalism/materialism/empiricism. He was therefore making a kind of metaphysical statement, albeit anti-metaphysics. He and the others you mention are unwilling to contemplate the possibility that there is something more to the universe than what is perceivable by our 5 senses.