"Some Christians have no idea of what goes on inside a synagogue," said Bob Ferguson, a former Lutheran who is now a member of Congregation B'nai Tikvah in Walnut Creek. "They often call our place a church."

In hopes of furthering ties between Christians and Jews, Ferguson is joining members of four synagogues and several Christian churches to undertake what he and Rabbi Gordon Freeman call "mitzvah" projects.

Held at 21 locations throughout the county, tasks include cleaning city parks, beautifying a women's shelter, refurbishing an elementary school, visiting people with AIDS, making and delivering gifts for seniors and maintaining an urban hiking trail.

"As members of the Jewish community, we need to find allies. We must find those who believe we are responsible for each other and are accountable before God," said Freeman of Walnut Creek's Congregation B'nai Shalom. For the past two years, Freeman has organized mitzvah days at his own synagogue.

The blueprints for the project were drawn after Freeman spoke last year during a Thanksgiving Day service at Grace Presbyterian Church in Walnut Creek. The Conservative rabbi described his vision of churches and synagogues joining together to work toward tikkun olam (healing the world).

After noting the enthusiastic response, Freeman sent invitations to houses of worship throughout his area, asking them to join Congregations Together. Three Jewish congregations and four Christian churches replied.

"I thought it was wonderful how I was able to share a vision and they were able to share it back to me," Freeman said.

Participating in the project are Congregations B'nai Shalom and Congregation B'nai Tikvah, Temple Isaiah in Lafayette and Danville's Beth Chaim Congregation.

The Christian responses came from four mainstream Protestant denominations.

The groups that attend "are those supportive of other people's faiths," said Rev. Roger Reaber of Grace Presbyterian Church.

One of the Congregations Together projects, involving members of B'nai Tikvah and the Contra Costa County Council of Churches, will help sponsor vaccinations of local children from low-income families. Although Contra Costa County has a 65 percent immunization rate among children, Congregations Together hopes to increase the rate to 80 percent.

"When it comes to biology and health issues, Jews and Christians can find a common ground," said Rabbi Raphael Asher of B'nai Tikvah.

Asher added that Jews and Christians need to understand each other better.

"The belief that all Christians are out to proselytize Jews is erroneous. True, we had experiences in history with that, but that's not true with today's liberal Christian groups," Asher said.

"It's wonderful to do gemilut chasadim, acts of lovingkindness, with people of various faiths," said Rabbi Dan Goldblatt of the Beth Chaim Congregation. "And doing tzedakah forms Ca very powerful connection, a God connection, not only within our own spiritual community but with others."

The day will conclude with a celebration from 7 to 9 p.m. at the Contra Costa Jewish Community Center, 2071 Tice Valley Blvd., Walnut Creek.