"...the priests of all these cults, the singers, shouters, pr..." — Upton Sinclair quote meaning

...the priests of all these cults, the singers, shouters, prayers and exhorters of Bootstrap-lifting have as their distinguishing characteristic that they do very little lifting at their own bootstraps, and less at any other man's. Now and then you may see one bend and give a delicate tug, of a purely symbolical character: as when the Supreme Pontiff of the Roman Bootstrap-lifters comes once a year to wash the feet of the poor; or when the Sunday-school Superintendent of the Baptist Bootstrap-lifters shakes the hand of one of his Colorado mine-slaves. But for the most part the priests and preachers of Bootstrap-lifting walk haughtily erect, many of them being so swollen with prosperity that they could not reach their bootstraps if they wanted to. Their role in life is to exhort other men to more vigorous efforts at self-elevation, that the agents of the Wholesale Pickpockets' Association may ply their immemorial role with less chance of interference.