Muslims throughout Temecula and Murrieta have saved up for years to build a mosque to replace the plain white industrial building, tucked between a pipeline company and packaging warehouse, where they now gather to pray.

But as the Islamic Center of Temecula Valley moves ahead with plans to build on a four-acre plot of vacant land near Temecula’s gentle hills and invading housing developments, plans for the new mosque have stirred hostility in this mostly conservative community in southwest Riverside County.

Along with increased traffic and noise, opponents fear the mosque would clash with Temecula’s rural atmosphere and, they say, possibly turn the community of 105,000 into a haven for Islamic extremists.

The pastor of Calvary Baptist Church, just across a cul-de-sac from the site of the mosque, said the two religions “mix like oil and water” and predicted a “confrontational atmosphere” if the project moves forward.

“The Islamic foothold is not strong here, and we really don’t want to see their influence spread,” said Pastor Bill Rench.

“There is a concern with all the rumors you hear about sleeper cells and all that. Are we supposed to be complacent just because these people say it’s a religion of peace? Many others have said the same thing,” he said.

Leaders of the Islamic center were surprised by the level of criticism, especially from a few religious groups, saying their current makeshift mosque and Islamic community center have been in town for more than a decade and members always have felt welcome.

“Our children go to the same schools their children go to. We shop at the same stores where they shop,” said Mahmoud Harmoush, the imam of the Islamic center and an instructor at Cal State San Bernardino’s World Languages and Literatures Department.

“All of a sudden our neighbors wake up and they’re opposed to us building the Islamic center there, the mosque. I hope it’s a small group,” he said.

The mayor and members of the City Council did not respond to calls about the issue. Temecula’s city attorney advised them not to comment about the proposed mosque because the Planning Commission’s vote on the application for the facility could be appealed to the council.

The Rev. Joe Zarro, co-chairman of the Interfaith Council of Temecula and Murrieta Valley, said criticism of the mosque in the community is from a very small but vocal minority. The council, made up of leaders of a variety of faiths in the area, including Harmoush, unanimously endorsed plans for the mosque, Zarro said.

“A lot of this has been blown out of proportion,” said Zarro, the minister at the United Church of the Valley. “It’s important for people to see our neighbors, and for them to be part of our community.”

The land for the proposed mosque lies west of the Temecula wine country in a pocket of the city that’s become a mish-mash of ranch homes with large grassy spreads and clusters of encroaching red-tile roofs. Along with Calvary Baptist, the mosque will be a short walk from Grace Presbyterian Church.

The design of the 24,943-square-foot mosque and center reflect a Mediterranean design seen in many Temecula neighborhoods, though the building will have traditional domes topped with crescent moons. The facility will be built in two stages, with the first limited to a 4,100-square-foot mosque to serve about 150 Muslim families living in Temecula, Murrieta and surrounding communities, Harmoush said.

The Islamic center has owned the land since 2000, but the small Muslim community has needed time to raise enough money to build. Harmoush said it could be years before the entire mosque and community center are completed.

The proposal is expected to go before the Temecula Planning Commission in August, and city officials are reviewing the expected effect of the mosque on neighborhood traffic and noise levels and any other environmental concerns.

“We look at land issues, that’s it,” said Patrick Robinson, director of the city’s planning and redevelopment agency. “We don’t take into account the denomination of the religion or any of the political issues that surround it.”

A petition opposing the new mosque is being circulated by a group called Concerned Community Citizens, and other politically active volunteers have started organizing a campaign against the facility.

Karen Fesini, who belongs to a Republican women’s group in the Temecula and Murrieta area, said she’s been making calls to warn her friends about the project.

“They say they’re not radicals, but how do we know?”’ said Fesini, 68.

“Right now we’re at war with the Taliban and the Muslims and our boys are over there fighting and dying for our freedom. What would it be like if they come home and found out we just let them in the front door?”

phil.willon@latimes.com