An idea or institution may arise for one reason and be maintained for quite a different reason.

The absence of theistic belief...

The making of an Atheist implies a mental stimulation and training which brings into play the primary factors of social progress.

The Rationalist case needs no straining of evidence and always gains by the severest self-criticism.

Not material or economic conditions in the ordinary sense, but perverse religious ideas explain the suspension of civilization in Europe from the 5th to the 12th century, and in the Mohammedan world after the 15th century.

Creeds made in Dark Ages are like drawings made in dark rooms

The Papacy was corrupt for whole centuries: especially from about 880 to 1050 and (with a short decent pontificate at rare intervals) 1290 to about 1660. No 'primacy' in any other organized religion has so disgraceful a record.