But in targeting grieving families of troops killed overseas, taunting people entering other churches and carrying signs with anti-gay slurs and vulgar language or symbols, Phelps and his Westboro Baptist congregation created public circuses that may have helped the gay-rights movement.
Following Phelps' death Wednesday at age 84, some gay-rights advocates suggested that he and his church created sympathy for lesbians, gays, bisexuals and the transgendered. Religious leaders who oppose gay marriage also said the pastor's tactics clouded the debate over such issues and put them on the defensive in discussing both policy and faith.
"The world lost someone who did a whole lot more for the LGBT community than we realize or understand," said Cathy Renna, a longtime consultant to LGBT groups. "He has brought along allies who are horrified by the hate. So his legacy will be exactly the opposite of what he dreamed."
Phelps founded the church in the 1950s, and it has drawn much of its small congregation from his extended family. Its rise to national and even international notoriety began in the early 1990s, as it picketed against gays and lesbians, then protested funerals of AIDS victims and, eventually, fallen soldiers.
The protests sparked outrage, with the federal government and lawmakers in more than 40 states passing specific laws to limit the protests and local residents using various tactics - including lining up to block views of the protesters - to protect grieving families.
Conservative religious leaders regularly denounced Phelps, worried that his relentless attacks would be perceived as representing the Christian case against same-sex relationships. At the 2003 annual Southern Baptist Convention, leaders spent a session drawing a distinction between their opposition to same-sex unions and Phelps' protests.
Phelps called his church Baptist but had no ties with the Southern Baptist Convention or any other mainstream Baptist group.
"Westboro Baptist is to Baptist Christianity what the "Book of Mormon" Broadway play was to the Latter-Day Saints," said the Rev. Russell Moore, who leads the Southern Baptist Convention's Ethics and Religious Liberties Commission. "They were kind of a performance art of vitriolic hatred rather than any kind of religious organization."
Phelps professed not to care what anyone thought of his church. He said in a 2006 interview with The Associated Press that no minister could "preach the Bible" without preaching God's hate. Westboro spokesman Steve Drain said in an email a few days before Phelps' death that the church's doctrines weren't changing.
"The church of the Lord Jesus Christ does not rise or fall with any man - in fact, the Lord doesn't need ANY of us," Drain wrote. "Any nation that embraces that sin as an 'innocent' lifestyle can expect to incur the wrath of God."
Some gay-rights advocates argued that Phelps and his congregation were problematic for the religious right because they said what social conservatives truly believed but were careful not to publicly express.
"Fred was a loathsome creature," said Wayne Besen, executive director of the gay-rights group Truth Wins Out. "But I'll say one nice thing about him: He's the only honest person on the religious right I've ever met."
Phelps often reserved especially caustic comments for evangelical Christians and Catholics who view homosexual behavior as sinful but also preach that God also loves and reaches out to gays and lesbians. Phelps dismissed them as "enablers," and his congregation often picketed their churches.
The Rev. Terry Fox, a Southern Baptist minister who's pastor of Wichita's non-denominational-leaning Summit Church, once felt compelled to apologize for Phelps' shocking behavior on television. Fox called Phelps "a false prophet" and said Satan "greatly used him." Fox was prominent in a successful effort in 2005 to persuade voters to amend the Kansas Constitution to ban gay marriage and said Phelps "was an embarrassment" but had "become the face of Christian work in Kansas."
Michael Schuttloffel, executive director of the Kansas Catholic Conference, said Phelps and his congregation still represent "an easy device" for gay-marriage supporters to "short-circuit the conversation" on that and related issues in recent years.
"People were justifiably, appropriately outraged by the things that they did," Schuttloffel said of Phelps and his church. "As soon as someone, then, is able to tar you as being related to them or thinking the same way as them, right away you're starting behind the eight ball."
Gay-rights advocates, meanwhile, were assessing Phelps' place in the history of their movement.
"An obscene footnote" is how Tom Witt, executive director of Equality Kansas, the state's leading gay-rights group, believes Phelps and his followers will be remembered. Witt said progress began well before Westboro's protests and will continue long after Phelps' death.
However, James Esseks, director of the Lesbian, Gay, Bisexual and Transgender Project at the American Civil Liberties Union, acknowledged that he eventually saw Phelps' protests as helping his own movement.