They talked about their experiences in a church rebuilt as well -- St. Paul's Cathedral, damaged by the April 19, 1995, bombing of the Alfred P. Murrah Federal Building.
Each of the six who spoke Sunday told how violence had changed their lives forever.
Their gathering marked the U.S. debut of The Forgiveness Project, a British exhibit of the photos and stories of both victims and perpetrators of violence.
Michael Berg's son, Nick Berg, 26, was beheaded in Iraq.
Berg told about 50 who came to the discussion he had forgiven those who brutally killed his son.
"Seeking vengeance on them only served to continue the cycle of hate," Berg said. "When we seek to even the score, we rarely do."
Murrah bombing survivor and panelist Susan Urbach attends St. Paul's, as she did at the time of the bombing.
Urbach said while the bombing injured her, the most devastating injury was done to her community -- her parish, friends, even her local post office.
She grappled with the idea of justice, she told the audience Sunday.
"It will never be the same as it was. No conviction will ever bring back one life," Urbach said. "Even justice has its limits."
Many on Sunday's panel said the path to forgiveness involved meeting the families of those responsible for their losses.
Bud Welch, whose daughter Julie was 23 when she died in the Murrah bombing, visited the house of Bill McVeigh, Timothy McVeigh's father.
Welch said he sat in the kitchen, staring at the family snapshots that lined the wall.
"The largest photo was an eight-by-ten of Tim. I kept glancing at the picture and felt the need to make a comment. So I said 'What a good looking kid,'" Welch said.
"He said 'That's Tim's high school graduation picture.' And a tear rolled down his check. That's when I recognized the love a father has for their child."
The exhibit runs today through Saturday.
NEWS 9 report
Crowd pays tribute with candles
