I think it's more that the natural emergent properties of a large number of agents interacting (like "the invisible hand of the market") sounded a lot like "the hand of God"

It's a pretty complex topic to put into words, and he was explaining self governing economic forces to people who had never heard of anything like that before... He was very carefully trying to avoid any religious or mystical implications, which makes everything come off awkwardly to an audience that understands these concepts already