One way in particular that we [the Interfaith Amigos] have found for the three Abrahamic faiths to meet each other and either begin or deepen the interfaith dialogue is through the celebration of what we call a Three-Day Shabbat. Friday is the main gathering day for Muslims, Friday evening and Saturday is Shabbat for Jews, and Sunday, although technically the Day of Resurrection, is celebrated as the Sabbath in the Christian community.
A Three-Day Shabbat invites a sharing of our rituals toward common purpose. The nature of the program you might create will depend on the degree to which interfaith dialogue already is taking place, but the design is simple and natural. The community gathers at noon on Friday, either at a mosque or at another place where Muslim prayer will take place. Christians and Jews can either witness or share the prayer with Muslims, and at a simple lunch afterward, talk together about the nature of that experience. Friday night or Saturday morning would be the sharing of the Jewish Shabbat, and Sunday morning would be Christian worship. No one would be asked to "water down" their tradition, but each would celebrate the deepest yearnings of their own faith. Saturday and Sunday afternoons can provide further time for study and for discussion.
— Don Mackenzie, Jamal Rahman, Ted Falcon in Getting to the Heart of Interfaith