Holy Roller meaning (derogatory): definition

Holy Roller

noun

Etymology From the practice of some devout Pentecostals who would roll on the floor of the church in response to the infilling of the Holy Spirit.

Derogatory, Informal, Usually A member of any Christian church characterized by ecstatic behaviour; especially of the Pentecostal Church.

I attended a worship service where I was astounded to see holy rollers convulsing on the floor and speaking in tongues.
Holy Rollers and Jumpers come out / And they holler, they jump and they shout / Give your money to Jesus, they say / He will cure all diseases today1911, “The Preacher and the Slave”, Joe Hill (music):

4 more examples

Also there are the "Holy Rollers" and "Holy Jumpers", ghastly sects which cultivate the religious hysterias, and have spread like a plague among the women of our lonely prairie farms and desert ranches.1917, Upton Sinclair, The Profits of Religion […] :
He told her the Methodist had at last broken down and cut the strip of grass himself. Mother believed it but wasn't pleased; she talked all the rest of the day and off and on all week about suing the old holy-roller.1960, John Updike, 'Rabbit, Run', page 20:
At the narrowest, Wasps form a select band of well-heeled, well-descended members of the Eastern Establishment; at the widest, they include Okies and Snopeses, "Holy Rollers" and hillbillies.1969 January 17, “Essay: Are the WASPS Coming Back? Have They Ever Been Away?”, in Time, →ISSN:
They took advantage of her, these holy rollers. When she was at death's door, they preyed on her faith and her fear. When she was no longer able to make rational decisions, persuaded her to give away our land for that amusement park.1989, Leon Capetanos, Fletch Lives, spoken by Hamilton Johnson (Hal Holbrook):

Derogatory, Informal A devoutly religious Christian person.

She's such a holy roller that she steers every conversation around to the joys of religion.