The gospel was preached universally even earlier than Moses! Here's a bit of a gem in Wiliam Haslam's (the guy who was converted as he was preaching!) autobiography:
My attention was directed to Cornish crosses; about which I also sent a paper, with illustrations, as a good secretary and correspondent to the same Journal. My researches on this subject took me back to a very remote time. I found crosses among Roman remains, with inscriptions, something like those in the Catacombs near Rome--these were evidently Christian; but I found crosses also among Druidic antiquities. I could not help inquiring, "Where did the Druids get this sign?" From the Phoenicians. "Where did they get it?" From the Egyptians. "Where did they get it?" Then I discovered that the cross had come to Egypt with traditions about a garden, a woman, a child, and a serpent, and that the cross was always represented in the hand of the second person of their trinity of gods. This personage had a human mother, and slew the serpent which had persecuted her.( These traditions came to the Egyptians from an ancestor who had come over the flood with seven others.)
Here was a wonderful discovery! The mythology of Egypt was based on original tradition, handed down from Antediluvian times! From further investigation, it was evident that the substance of Hindoo mythology came from the same source; as also that of the Greeks, Chinese, Mexicans, and Scandinavians. This is how the Druids got the cross also: it was in the hand of their demi-god Thor, the second person of their triad, who slew the great serpent with his famous hammer, which he bequeathed to his followers.
I was beside myself with excitement, and walked bout the room in a most agitated state. I then made a table or harmony of these various mythologies, and when placed side by side, it was quite clear that they were just one and the same story, though dressed up in a variety of mythological forms, and that the story was none other than that of the Bible.
In my architectural journeys I used to entertain, people with these wondrous subjects; and one evening I had the honour of agitating even the Bishop of Exeter himself, who, in his enthusiasm, bade me write a book, and dedicate it to him. I did so. "The Cross and the Serpent" is the title of it, and it was duly inscribed to his lordship. [http://www.4shared.com/document/Pik5a6zD/William_Haslam_-_The_Cross_and.html]
It excites me even now to think about it, though it is thirty-five years since I made these discoveries. The old librarian at Oxford declared that I was mad, and yet he could not keep away from the subject, and he was never weary of hearing something more about it. This reverend Doctor said, "If you are right, then all the great antiquaries are wrong." I suggested that they had not had the advantage I possessed of placing their various theories side by side, or of making their observations from my point of view.