What is meant by God is the Most High - the greatest of all perfections, the first of all causes, the highest of all natures, the most necessary of all beings. Given that there is a gradient of perfections in nature (inanimate to animated, unintelligent to intelligent, irrational to rational, material to spiritually-inclined, dark to bright, etc), and given the principle of proportional causality where causes must be greater than their effects, and given that there cannot be an infinite regression of perfections in causes, then there must be a most perfect cause. Given that there are effects in nature that are not themselves eternal, and thus must have been caused by something else, and given that there cannot be an infinite regression of efficient causes, there must be a First Cause. Given that there is contingent being (i.e. being that depends on something else to exist), and given that there cannot be an infinite regression of contingent beings, then there must be an absolutely necessary being somewhere at the beginning. Whatever this first cause, this highest perfection, this greatest nature is, I call Him God - and I attribute Personhood to Him because a Person is a higher nature than a non-person, and so in an analogical or virtual sense I view this as more appropriate than to call God an "it". So the very existence of contingent being, and caused effects, and lower perfections serves as the evidence for God's existence. The existence of sky fairies, however, I do not defend.