Fred Phelps, the patriarch of the Westboro Baptist church who was notorious for his relentless campaign against America’s acceptance of homosexuality, has died at 84.

Steve Drain, an elder at the church, told the Guardian: “Fred Phelps died at about 11.15pm on Wednesday.” Phelps’s daughter Shirley told the Topeka Capital-Journal that her father died at a hospice in Topeka, Kansas, following a period of illness.

In a defiant post on its official blog, the church – from which Phelps had reportedly been excommunicated in recent years – declared that its controversial work would go on.

“God forbid, if every little soul at the Westboro Baptist Church were to die at this instant, or to turn from serving the true and living God, it would not change one thing about the judgments of God that await this deeply corrupted nation and world,” it said.

Phelps, who according to the church had 13 children, 54 grandchildren and seven great-grandchildren, founded Westboro in 1955 but earned notoriety in the 1990s when he began leading followers on noisy protests against gay people around the US.

An era of intense national media coverage was kickstarted by their picketing the 1998 funeral of Matthew Shepard, a gay 21-year-old student from Wyoming, who was tortured and killed in what was said to be a hate crime. “Matt In Hell,” said one of Phelps’s signs.

After several years spent picketing more memorial services, including those of people who had died of Aids, Phelps and his church provoked even more widespread anger after the terrorist attacks of September 11, which Phelps described as a “glorious sight”.

They began picketing funerals of US troops killed in Iraq or Afghanistan, who they called victims of divine retribution for tolerance of homosexuality. “The Lord is punishing this evil nation for abandoning all moral imperatives that are worth a dime,” Phelps said in 2005.

Bystanders discuss scripture with members of the Westboro Baptist church as they picket outside of the supreme court in 2010. Photograph: Keystone USA/Zuma/Rex Photograph: KeystoneUSA-ZUMA/REX

Phelps, his relatives and other members of the church brandished distinctive placards declaring “God blew up the troops,” “Thank God for 9/11” and other slogans that caused dismay, pleas to stay away, and – seemingly most important for Phelps – publicity.

Their extreme views led to Westboro being declared a “hate group” by the Southern Poverty Law Center and the Anti-Defamation League – and to fallouts with prominent evangelical Baptist preachers such as Billy Graham and Jerry Falwell.

The Phelps clan’s notoriety grew wider still in 2007, thanks to The Most Hated Family in America, a documentary made by the BBC’s Louis Theroux. Among other scenes, one showed Noah, one of Phelps’s grandsons, decrying the US as a “nation of fags”.

Phelps was born to a poor family in Mississippi in 1929, and was raised by his aunt after his mother died of cancer and his father was away working. He was admitted to the US military academy at West Point but left before graduating in order to become a minister.

He is survived by Margie, his wife of 52 years, whom he met at the Arizona Bible Institute in Phoenix. He had a law degree and practised in Kansas. Relatives have said he took on lucrative civil rights cases while espousing racist views at home. He was disbarred in 1979 for unethical behaviour during a trial in which he also called a witness a “slut”.

Phelps attempted to enter public office in the early 1990s, running unsuccessfully in the Democratic primary contests for the Kansas governorship in 1990 and for one of its US Senate seats in 1992, when he publicly referred to his opponent as a “bull dyke”.

Two of Phelps’s sons, Nathan and Mark, left the church when they became adults and have become vocal critics of its teachings in recent years. They said Fred Phelps was “excommunicated” in 2012 after advocating a softer line. The church has repeatedly declined to comment.

Pastor Fred Phelps in Washington in 1998. Photograph: Nina Berman/Sipa/Rex Photograph: BERMAN NINA/SIPA/REX

Nathan has said that Phelps subjected his children to “extreme physical punishments and abuse, extreme dietary and health requirements, and other extreme expectations”. He told an interviewer last year: “He had this old barber’s strap and used it so much that the last six inches were frayed, kind of like a cat-o-nine-tails, and he’d hit you with it and it’d wrap around your hips and rip the skin.”

Mark told Jon Michael Bell, the author of Addicted To Hate, a book about Phelps and the church, that his father once beat him so brutally that “I was hoping I’d be knocked out, or killed ... anything to end the pain.” Loyal family members denied that he was violent.

In 2012, Megan and Grace Phelps-Roper, two of Phelps’s grandchildren, became the latest members of the family to leave the church and admitted: “We hurt a lot of people.” Still, Grace dedicated a blogpost to their grandfather this week in which she criticised media depictions of Phelps and said: “To the whole world you were only ever the face of an evil entity. But of course to me you were always my Gramps.”

Phelps and his church faced a barrage of lawsuits and legal actions by those who attempted to stop their pickets. Their right to continue protesting was, however, ultimately upheld by the highest court of the nation they said was damned.

In March 2011, the supreme court upheld an appeals court verdict rejecting a $5m award by a lower court to the father of Lance Cpl Matthew Snyder, a US marine killed in Iraq, whose funeral was picketed by Phelps’s church. The justices ruled 8-1 that the Phelps clan’s protests were protected by free speech.