Our Rialto Church Center was formerly St. Thomas Moore Church which was founded by Fr. Albert Schwartz in 1961. The first Mass of this Church was celebrated in the Priest's Rectory and later Masses were celebrated in a remodeled two room schoolhouse on Riverside Avenue where the Y.W.C.A. later stood. When Fr. Daniel O'Callaghan became the first pastor of St. Thomas Moore in 1961, he began immediately to look for a new site for the location of the Church building. Meanwhile the Holy Mass was celebrated at the Rancho Verde Country Club and at the Lutheran Church of the Cross pending the building of a permanent Church house. In 1965, the present Church property was purchased on Easton Street. On this new ground, a hall was built and dedicated by Bishop Buddy to serve as a place for celebrating Mass at the meantime. In 1968 Fr. Timothy Harnett became the second Pastor. The parish grew very rapidly at the time, and on December 22, 1966, the first Confirmation class was confirmed by Bishop Furey.
In 1968, an Adult Choir was formed under the direction of William Priestly. This Choir was seconded by the Catholic Youth Organization (CYO) which was very active at the time and sang regularly at Folk Masses. It was in this same year (July 4, 1968) that the first Mexican Fiesta was held with Mrs. Manuel de la Vega and Lupe Ross as Co-Chairpersons. In 1970 Fr. Thomas Healy became the third pastor of St. Thomas Moore. A new Parish Church construction was signed in 1971 by Bishop Maher. The construction of the new Parish Church was completed in April 1972. In 1974 Fr. Richard Waterfall became the fourth Pastor of the parish.
In 1974 the Altar Society began sponsoring funeral receptions for all parish families. In 1978 Fr. Thomas Gillespie became the fifth pastor of St. Thomas Moore. By 1980 the first Parish Council was formed, and Bishop Phillip Straling ordained Tom Brannick as a permanent Deacon for the parish. In 1981 Sr. Eileen Rafferty was appointed Pastoral Assistant, and the Parish Hall was enlarged with offices to provide accommodation for the administrative staff. The Statue of the Blessed Virgin Mary was installed and dedicated by Bishop Straling in 1985. On October 18, 1986 a Mass of Thanksgiving was celebrated to mark the 25th Anniversary of St. Thomas Moore Church.
By 1991 St. Thomas Moore received her sixth pastor, Fr. Edward DuBel, CR. With a growing Spanish Speaking families arriving to the parish location area, a need for a Spanish Mass became expedient. Thus in 1993 St. Thomas Moore Church celebrated her first Spanish Mass. Unfortunately, in 2001 the Statue of the Blessed Virgin Mary was vandalized but later replaced with a new one in May 5th at the 21st Annual Madonna Tea. Throughout the length of the church's existence the Religious Education, Liturgical Ministries and more recently the Hispanic and Filipino Ministries have been an integral part of the parish. The seventh and last pastor of St. Thomas Moore Church before it became part of the present parish was Fr. Timothy Jenejcic. In 2006, St.Thomas Moore Church combined with Resurrection Church in Fontana to become Saint John XXIII.