Jews will begin celebrating Rosh Hashana, the Jewish New Year that also begins the 10-day period known as the "Days of Awe." And if the first moon sighting goes as some are predicting, Muslims will usher in the holy month of Ramadan that same day.
Even if the crescent moon cannot be seen Oct. 4, the religious holidays will see an unusual convergence in the same week. Christians are in on the action as well, marking Oct. 4 as the Feast of St. Francis of Assisi, a relatively minor holiday mostly commemorated by Roman Catholics.
Across the country, religious communities are using the calendar's coincidence as a launching pad for interfaith projects around topics ranging from the political to the spiritual.
Rabbi Arthur Waskow, director of the Philadelphia-based Shalom Center, a national peace and justice organization, has dubbed the confluence of holidays "God's October Surprise."
Waskow has organized a series of events inspired by the simultaneous holidays, which he says form a "prophetic teachable moment" that can allow local communities to think more deeply about how they can connect with people of other faiths.
In Philadelphia, Waskow has planned a day of ecumenical reflection and discussion, featuring workshops that focus on political issues including gun violence, terrorism and war, the environment, poverty and responding to the victims of Hurricane Katrina.
The event will take place near the Liberty Bell on Oct. 23. Since that's a Sunday, it allows Christians to attend after church. On that day, Jews will be celebrating Sukkot, the harvest festival during which they build an outdoor open structure, or sukkah. And Muslims will be observing their daily fast for Ramadan.
Waskow, who is calling on members of all three faith communities to fast that day as a gesture of solidarity, says the confluence of holy seasons opens doors for interfaith communication that is urgently needed.
"At this moment, more than most in the previous generation, these three traditions are being dragged by some elements in each of them -- not majorities -- but they are being taught to voice hatred or even to act violently toward one or both of the others," he said.
"It takes proactive, reconciliatory action to point us back to the direction that most people in these three traditions think that God intended," said Waskow.
"The fact that there's something going on that's encouraging people who are inclined to reach out to people of other faiths just as human beings, I think that's significant," said Imam Al-Hajj Talib Abdur-Rashid, spiritual leader of the Mosque of Islamic Brotherhood in New York's Harlem neighborhood.
Abdur-Rashid, who will be organizing an interfaith event around the holidays in Harlem and is aware of several others around New York City, said that the joint celebration of October holidays is a continuation of previous interfaith efforts, not the beginning.
"We're looking forward to whatever little boost (the holidays) might give," he said.
For other religious leaders, the triple-holiday points out the ways in which efforts to achieve interfaith understanding have not yet come to fruition.
The Rev. Robert Morris, an Episcopal priest and executive director of the Summit, N.J.-based interfaith community organization Interweave, says there's an "urgency" among those, particularly clergy, who want to reach out to people from other faiths. But there is also, he said, a "helplessness" because many of them "don't feel very skilled" in making those connections.
"There's not enough experience to feel confident in reaching out in interfaith relations on the part of local leaders," Morris said.
Interweave is helping to organize a program on Oct. 9 that will bring together leaders from Judaism, Christianity and Islam to discuss the themes of repentance, reflection and renewal in the three traditions. Those ideas are at the core of both Ramadan and the Jewish High Holy Days, and they also figure into Christian theology.
Nationwide, religious leaders are also organizing "break-fasts" on Oct. 13. In addition to being a day of Ramadan, during which Muslims fast from sunrise to sunset, that date is also Yom Kippur, the solemn day of repentance during which Jews fast for a 24-hour period.
In Boulder, Colo., Jewish, Christian and Muslim leaders are focusing on the spiritual connections they might form around this unique religious moment.
At Pardes Levavot, a Jewish Renewal congregation that shares space with a Lutheran church, the end of the Yom Kippur service will become an interfaith experience, said Rabbis Victor and Nadya Gross, who lead the congregation.
The last hour of the traditional Yom Kippur service, called "neilah," is an intense period of prayer during which Jews believe that the "gates of prayer" -- which opened on Rosh Hashana allowing them to ask God for forgiveness -- will close until the next year.
This year, Muslims and Christians will be present during the neilah service, and the three groups will break their fasts together (the church is also calling for Oct. 13 to be a day of fasting).
Symbolically, said Nadya Gross, the moment will bring a spiritual element to what they hope will be an ongoing relationship built across faith lines.
"Certain gates are closing, but we are opening new gates, gates that allow us to enter into a new space together," she said.
The October religious holidays are not just being marked in large cities with diverse populations.
In Traverse City, Mich., in the northern part of the state, Rabbi Chava Bahle of Congregation Ahavat Shalom, an independent synagogue with around 60 member families, has organized a concert for Oct. 29, called "Building Bridges, Making Peace."
The concert will feature storytelling, music and prayer from many faiths, including presentations by some Muslim students at an area high school.
The way the small town is coming together for the evening is inspiring to Bahle.
"It's so exciting that so many communities are recognizing this confluence," she said, "It's very holy."