Sinclair, Upton (1878-1968) - The Profits of Religion (orig. publ. 1917, 5th ed. 1926)

More profitable reading (forgive the poor pun): Sinclair takes the scammers and redemption-dealers of his time head-on and switches the light off their halos. From established churches that rip off their lambs in many economic ways, to groups that abuse and mistreat their members to cheaters and liars, from the Christian fringe via the esoteric to spiritist cults (which were veeery popular until the late 1930s and spawned several orgs still operating their franchises to-day). I stumbled across this book when looking up Mazdaznan at Wikipedia (a supposedly ancient Zoroastric cult founded by a German emigrant's son in the US around 1900 and marketed to the world; curious because it had a strong following in early Bauhaus, which influenced modern design and architecture like no other school in the world... and they held Mazdaznan meetings and performances, etc. ...), and they are just one example of many professionals who proclaim to "do holy", when all they do is milk their followers and hard-sell faith. Originally published 1917 under the impression of World War I (which adds some colour). Appened with the Wikipedia-article on Upton Sinclair.

"And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God." -- 'nuff said.