The signs went up in September and read: “In any war between the civilized man and the savage, support the civilized man. Support Israel. Defeat Jihad.”

Ahmed Rehab, the executive director of the Council on American-Islamic Relations’ Chicago office, said he was surprised that the New York case focused only on the word “savage,” not jihad — an indication, he said, that the Muslim community needed to be more active about promoting a more peaceful interpretation of its beliefs.

“Unfortunately we have witnessed in front of our very eyes a central tenet of our faith essentially become tarnished,” Mr. Rehab said of the controversy, adding, “I was tired of hearing fathers tell their children, you know, ‘Don’t say jihad over the phone. Don’t say jihad in public.' ”

He took to Facebook, posting a childhood story about his bedridden grandmother, who had once described coping with her ailing health as “my jihad.” He started raising money, held meetings in living rooms and started the campaign in December with ads that ran on 25 buses in Chicago. The ads have since spread to buses and subway billboards in San Francisco and Washington.

“Loving a challenge, loving a jihad if you will, I wanted to take this on,” Mr. Rehab said.

David Cook, professor of Islamic studies at Rice University, said that the term jihad had for centuries been associated with “God-sanctioned violence,” but that progressive Muslim groups have been talking about peaceful interpretations since the late 1800s. While he was unaware of other public relations campaigns focusing on the word jihad before Mr. Rehab’s, Professor Cook said the push fit into a larger concerted effort by Muslim groups to explain aspects of their religion to the broader American public since the Sept. 11, 2001, attacks.