The two actors were photographed at a protest in Venice, California, on Tuesday amid several other protesters who were denouncing the demolition of the First Baptist Church of Venice. The photo was shared on Twitter by the @savexvenice account.
Affleck, 47, wore a dark gray T-shirt and a matching sweater and held up two signs, one of which read, "Save First Baptist Church of Venice," while a smaller one read, "Black Lives Matter."
De Armas, 32, stood beside him in a black tank top and jeans, as she clapped her hands.
A friend of Affleck's tells PEOPLE, "Ben wants to continue to be a model for his children. They talk about these important issues."
The Twitter account caption read, "March for #GeorgeFloyd in #Venice today. Blessed to have @BenAffleck express awareness and concern for the local Historic Black Community in #VeniceBeach that has been long ignored and obstructed by local politicians, LAPD, and commerce bullies. #SaveVenice #DefendOakwood."
The First Baptist Church of Venice was built in 1910 and has been a landmark building within the African American community — although its history is in danger of disappearing.
In February 2017, the church was sold for a reported $6.3 million to a private holding company with plans to remodel the church, which has been unoccupied since 2015, according to LA Curbed.
A spokesperson for PMC did not comment.
Many celebrities have shown their support for Black Lives Matter after the death of George Floyd, 46, last Monday in Minneapolis, Minnesota, when a white officer, Derek Chauvin, pinned him to the ground with a knee on his neck.
While Chauvin has been fired from his post and was charged with third-degree murder and manslaughter on Friday, public protest over racial inequality and police violence continues to spread in major cities across the nation.
Though Minneapolis remains the epicenter, there have been protests in at least 30 other U.S. cities, according to CNN.
Minnesota, Colorado, California, Washington, D.C., New York City, Georgia, Texas and Louisville, Kentucky — where Breonna Taylor, an African American aspiring nurse working as an EMT, lived before she was fatally shot by police in her home — all saw protesters march in peaceful rallies before ending in violent clashes with police.