On Saturday, members of Main Line Unitarian Church in Devon will hoist a yellow-and-black banner at South Valley Forge Road and Maplewood Avenue, in a jewel-green neighborhood of expansive homes and decorous sensibilities.

Two feet by seven feet, embellished with the outline of a heart, the panel will hang eight feet off the ground - maybe high enough, maybe not.

"Hopefully, nobody will be able to reach it," said the Rev. Neal Jones, who leads the 600-member church. "If they do, we'll just replace it."

The pastor knows the power, for good and ill, of the banner's message: "Black Lives Matter."

Throughout the region, as across the country, other predominantly white congregations - some galvanized by their denominations' social-justice agendas - have hung "Black Lives Matter" signs on their property, only to soon find them vandalized or stolen.

Nearby, in the heart of the Wayne business district on Lancaster Avenue, Central Baptist Church put one up last summer as part of a vigil for people killed in police-involved shootings. Complaining calls came in. Racist postings appeared on the church's Facebook page. The banner was vandalized repeatedly, once with an "X" painted over the word "Black."

In Cherry Hill, the Unitarian Universalist Church put up a banner in February to announce an upcoming forum. It was defaced four times.

In July, First Unitarian Church of Wilmington's sign was vandalized three times in a week, with the word "Black" cut out. Each time, it was replaced or repaired. Finally, a message was added warning vandals that "each time you come in the night . . . we will replace [the banner] and make a donation to a Black Lives Matter organization," said the Rev. Roberta Finkelstein.

No arrests have been reported in those cases.

Vandalism is no surety.

In Philadelphia, the Unitarian Society of Germantown's banner has survived intact since April. St. Luke Evangelical Lutheran Church in Devon, about two miles from Main Line Unitarian, posted "Black Lives Matter" on its message board without incident. Likewise Trinity Evangelical Lutheran Church in Lansdale, although it provoked significant angry feedback by phone and email.

Main Line Unitarian is undeterred.

The banner ceremony on Saturday will feature the Rev. Tom Beers of Central Baptist Church and lawyer Anita Friday of Berwyn. Her two sons were stopped by police last year as they rode their bikes in the upscale Greens of Waynesborough community, headed to a friend's house to swim. A suspicious resident had summoned the officers. The teens were African American.

Calling the banner a "prophetic statement," Jones said it is meant to spotlight the problem of racism, and to remind passersby in the Devon area - nearly 93 percent white - to "uphold the inherent worth and dignity of every person." Those words are printed as a footnote on the sign.

To others, though, "Black Lives Matter" implies that African American lives are more important than others. In it, some hear an antipolice rallying cry.

Jones met with the police chiefs in Radnor and Easttown Townships to assure them the banner was not intended as an affront to officers.

David Obzud, the Easttown chief, said the church was free to express its opinion. "I will defend their right to put up whatever they are allowed to put up," he said. "But after that, what you feel about the movement is an individual perception."

In a study released in July by the Pew Research Center, 43 percent of Americans said they supported the movement - begun in 2014 with the shooting death of Trayvon Martin - and 22 percent opposed it. Thirty percent offered no opinion.

Main Line Unitarian's denomination, the Unitarian Universalist Association (UUA), is among several faith groups that have stood up for "Black Lives Matter" or spoken out on issues of racial justice.

Last year, the UUA passed a resolution supporting the movement and encouraging its congregations to erect signs.

The African Methodist Episcopal Church's Social Action Commission has passed at least one resolution supporting most of the issues promoted by Black Lives Matter, said the Rev. Dr. Mark Kelly Tyler, senior pastor of Mother Bethel A.M.E. Church.

In May, the United Church of Christ introduced "White Privilege - Let's Talk," an adult education curriculum that is part of what the denomination describes as an "ongoing commitment to sacred conversations on race."

Main Line Unitarian began its own journey about a year ago, when Jones took the helm.

The congregation was taking part in a denominational program that selects one book for members to read each year. This time, it was Just Mercy, a memoir by African American lawyer Bryan Stevenson, who grew up in Milton, Del., graduated from Eastern University in St. Davids and Harvard Law School, and went to the South to represent poor clients.

Its theme of racial inequality prompted a member to suggest a "Black Lives Matter" banner.

Main Line Unitarian had already been down a similar path. Five years ago, to signal its openness to the LGBT community, it put up rainbow flags, which were repeatedly stolen. Eventually, the church resorted to wrapping multicolored tape around a light pole.

A "Black Lives Matter" banner was debated in an email thread and in meetings of the congregation, which has at most a dozen members of color.

"There were definitely some people who were uncomfortable with the banner," said Rich Fritzson, 62, a computer engineer from Paoli. "The common reaction was that it should say 'All Lives Matter.' "

Longtime member Nuala Carpenter, 72, was in favor of the banner.

"Yes, all lives matter," said the retired physical therapist from Wayne. "But black lives are really getting the short end of the stick in America. And not just the willful killing of unarmed young black men, but with economic disparity and schools struggling for resources."

Members voted in a secret ballot: 92 percent yea, 8 percent nay.

One opponent was so frustrated with the decision that he withdrew his financial support, Jones said. That member, who also had some issues with congregational governance, still attends the church, Fritzson said.

The congregation's statement is a courageous act, said the Rev. Naomi Leapheart, a Black Lives Matter activist and suburban organizer for POWER, an interfaith social justice group. It's expected "to see predominantly black churches say black lives matter," she said. "It's another [thing] for a congregation of means on the Main Line to assert it without apology" - and often at a cost, she added.

Yet, at churches where the banners have been vandalized, good has often come from bad. Neighbors have reached out to congregations to offer support, ministers say.

Central Baptist's trials with the sign have led to the founding of the Main Line Interfaith Undoing Racism movement, which includes representatives of 12 churches and two faith-based organizations.

The Unitarian Universalist Church of Cherry Hill will host another forum at 7 p.m. Sept. 20 to discuss police and community relations.

Neighbors of First Unitarian in Wilmington began donating money for more banners. The church has raised its sign 12 feet high, and installed motion detectors.