"As for the laymen, they are recruited from the wealthy class.

That explains why these scandals are hushed up if the police chance to discover them.
"Then, let us assume that the sacrifices to the Devil are not preceded by preliminary murders.

Perhaps in some cases they aren't.

The worshippers probably content themselves with bleeding a foetus which had been aborted as soon as it became matured to the point necessary.
Bloodletting is supererogatory anyway, and serves merely to whet the appetite.

The main business is to consecrate the host and put it to an infamous use.