Here's a quote from a nineteenth century theologian, Thomas B. Thayer indicating how long this "sacred fraud" has been going on and the perps' rationale.
Any one at all familiar with the writings of the ancient Greeks or Romans, cannot fail to note how often it is admitted by them that the national religions were the inventions of the legislator and the priest, for the purpose of governing and restraining the common people. Hence, all the early lawgivers claim to have had communications with the gods, who aided them in the preparation of their codes. Zoroaster claimed to have received his laws from a divine source; Lycurgus obtained his from Apollo, Minos of Crete from Jupiter, Numa of Rome from Egeria, Zaleucus from Minerva, &c. The object of this sacred fraud was to impress the minds of the multitude with religious awe, and command a more ready obedience on their part. Hence Augustine says, in his "City of God," "This seems to have been done on no other account, but as it was the business of princes, out of their wisdom and civil prudence, to deceive the people in their religion; princes, under the name of religion, persuaded the people to believe those things true, which they themselves knew to be idle fables; by this means, for their own ease in government, tying them the more closely to civil society." B. iV 32.
