A group of Greek Orthodox Christians lead by Fr. Leon Pachis, formed a mission church in Upland California after obtaining permission from His Grace Bishop Anthony of San Francisco in 1981. Prior to formation of the mission in the Pomona Valley few of these Greek Orthodox Christians would take the time to travel 27 miles to the east to go to St. Elias in San Bernardino or the alternative 26 miles to the west to go to St. Anthony's in Pasadena. Most of the Greek Orthodox Christians in the Pomona Valley area did not have the opportunity to attend Church regularly. 

         Immediately upon the formation of the mission 30 to 40 Greek Orthodox Christian families attended services which were performed by Fr. Leon Pachis and other Priests in the area at St. Marks's Presbyterian Church in Upland.

        In 1982 they purchased the property on 1391 Chaffee Street in Upland, California which is a mile from north of interstate 10 freeway and a little over a mile from the Ontario Airport. 

        In 1983. His Grace Bishop Anthony participated in the event of naming the church. Among the candidate names were St. George, St. Andrew, St. Demetrios, and St.Spyridon.  The name of St. Spyridon was selected as a result of the highest monetary contribution of Maria Colas of Claremont, California. The group continued to hold services at that location performed by Fr. Leon Pachis and other Priests in the area. 

        In 1987 Father George Manneh was appointed by His Grace Bishop Anthony as a full time priest for the new small parish.

        Over the years a number of dedicated parishioners remodeled the original building, Which now resembles a small church in Greece. Currently the Parish Council has undertaken the task of remodeling an old house adjacent to the church which will serve as a meeting place for all as well as the Priests office.