Just read from a biased source that “hocus pocus” was a mockery of the Latin mass that turned the bread and wine into the actual body and blood of Christ. I was skeptical of this origin, so looked it up.
“Many people today believe it originated in a corrupted form of the words of the consecration of the host in the old Latin mass: hoc est (enim) corpus (meum), “this is my body”, an idea first aired by John Tillotson, Archbishop of Canterbury between 1691 and 1694. But as this was part of an anti-Catholic sermon, it may be taken with a fair-sized pinch of salt.”
No one really know where it came from, but it was in use before this anti-Catholic sermon.