The first reason for this is that knowledge about God and therefore acknowledgment of God is not possible without revelation; and knowledge of the Lord and therefore acknowledgment that all the fullness of divinity dwells physically in him is not possible without the Word, which is a garland of revelations. From the revelation they have been given, people are able to meet God, receive an inflow, and thus be made spiritual instead of earthly.
Early revelation spread throughout the whole world, and the earthly self distorted it in many different ways, giving rise to divergences, disagreements, heresies, and schisms among religions.
The second reason [for the diversity of opinions on God] is that the earthly self cannot comprehend anything about God; it can comprehend only the world, and conform it to itself. This is why it is among the axioms of the Christian church that the earthly self is against the spiritual self, and that they battle each other. People then have come to acknowledge from the Word [or] from some other revelation that there is a God, and yet in both the past and the present they have had a diversity of opinions on the nature and the oneness of God.
Therefore people whose mental sight was dependent on their physical senses and who nevertheless wished to see God made idols for themselves out of gold, silver, stone, and wood. They intended to adore God in those forms as objects of sight. Others with the same desires but with religious principles that forbade idols pictured the sun and moon, the stars, and various things on earth as images of God. Those who believed themselves to be wiser than most but who remained earthly were led by the immensity and omnipresence God displayed in creating the world to acknowledge nature as God, in some cases in its innermost, in others in its outermost aspects. And some who wished to see God as separate from nature thought up some thing that was as all-encompassing as possible and that they called the Entity of All; but because they know nothing more of God than this, this “Entity of All” turns out to be an entity of their minds alone, utterly without any real meaning.
As anyone can see, concepts of God are mirrors of God, and people who know nothing about God do not see God in a mirror facing their eyes, but in a mirror that is facing the wrong way, the back of which is covered with quicksilver or some black, sticky substance that absorbs rather than reflects the light.
Faith in God enters us on a pathway that comes down from above, from the soul into the higher reaches of the intellect. Concepts of God enter us on a pathway that comes up from below, because the intellect takes them in from the revealed Word through our bodily senses. In mid-intellect the different inflows come together. There an earthly faith, which is mere belief, becomes a spiritual faith, which is actual acknowledgment. The human intellect, then, is a kind of trading floor on which exchanges occur.
from True Christianity, Volume 1, Section 11