The groundwork for this was the lifetime work of Wilhelm Schmidt, published in his Origin and Growth of Religion (English Ed. 1931), which you should be able to find in any university library. Schmidt found that, thoughout the world, primitive cultures have a notion of a supreme god. This god has the following characteristics - remarkably uniformly across the world:
The obvious response to all this is, "Where have I heard that before?" Because it sounds suspiciously like the Christian (and Jewish, and Muslim) picture of God.
There is also the question of why people - from all over the earth - have such similar conceptions of the Creator God.
My conclusion is this: the Biblical picture is that all people once knew the true God, but that people rebelled against him, and their knowledge of him was corrupted. The evidence of the "Sky-God" correlates with this. People have gradually corrupted their knowledge of the true God, often replacing it with man-made religion (idols etc.). The story of human religion is one of starting with the worship of the true God, and gradually falling away from that.
So the widespread belief in the "Sky-God" agrees with what we read in the Bible.
First, The Religious Experience of Mankind by Ninian Smart (Collins, 1969; page numbers from Fontana Paperback edition) p.53-55
THE HIGH GODSecond, Patterns in Comparative Religion by Mircea Eldiade (trans. R. Sheed; Sheed & Ward Ltd., 1958), p.38It is doubtful whether there is a supreme High God in the Ainu tradition. Nevertheless this idea is quite widely held by other primitive peoples. In most, if not all of the indigenous cultures of Africa there is a belief in a supreme spirit ruling over or informing the lesser spirits and gods. He governs natural forces,dwells on high, is inexplicable, creates souls, men, and all things. If the lower spirits and deities are more familiar and intimate... yet for many Africans such a God exists and is not altogether neglected in worship and prayer.
Thus, ruling over the world which teems with divinities and sacred forces, there is - high above in the sky, but not of the sky - some kind of supreme Being. Among many primitive peoples outside Africa a similar belief is attested.
This has led some scholars, notably Father Wilhelm Schmidt (in The Origin of The Idea of God, first published in 1912), to postulate a primitive monotheism at the dawn of human existence, a monotheism later overlaid by polytheistic beliefs and yet preserved in recognizable form in the religions of primitive peoples. This is a reversal of the usual position of those who have been influenced by evolutionary theory, who tend to equate 'later' religion with 'higher' religion, and who regard monotheism as the highest development of all... In any event it is a striking fact that many primitive cultures have a belief in some sort of High God, even though there very often is no specific ritual directed toward such a Being.
...
The existence of such conceptions among folk as far apart as the inhabitants of Tierra del Fuego [at the Southern end of Chile] and the Arctic is a significant indication that primitive religion... possesses sophisticated ideas about the beginning and creation of the world, and about a supreme architect of the world.
The most popular prayer in the world is addressed to "Our Father who art in heaven". It is possible that man's earliest prayers were addressed to the same heavenly father... The Vienna school of ethnology (particularly in the person of Fr. W. Schmidt, the author of the fullest mongraph yet on the subject of the origins of the idea of divinity) even claims to have established the existence of primitive monotheism, basing the proof chiefly on the belief in sky gods among the most primitive human societies. For the moment we will leave to one side the problem of primeval monotheism. What is quite beyond doubt is that there is an almost universal belief in a celestial divine being, who created the universe and guarantees the fecundity of the earth (by pouring rain upon it). These beings are endowed with infinite foreknowledge and wisdom; moral laws and often tribal ritual as well are established by them during their brief visit to the earth; they watch to see that their laws are obeyed, and lightning strike all who infringe them.