From: The Encyclopedia of Canada's Peoples/Assyrians/Arian Ishaya
Traditionally, the church has been the locus of community activities among Assyrians. It has played a crucial role in preserving the Assyrian language and cultural heritage. Consequently, the Assyrians of Canada lost little time in recreating ancient-rite churches, and within a decade of their arrival, four sanctuaries were purchased in Ontario with community and church funds. Most of the Assyrians in the province belong to the Nestorian Church of the East. The settlement in Toronto is the largest and the best organized. Its Holy Apostolic Catholic Assyrian Church of the East, with a membership of 450 families, was established in 1977. The building was purchased two years later. The church has a quarterly publication titled Scholion (Toronto, 1990– ), issued in three languages: Assyrian, English, and Arabic. In addition, the Mar Narsai Society, an associated youth organization, conducts religious and Assyrian language classes for children at the church. It is also affiliated with Church of the East youth organizations throughout North America. Annual conventions bring young people together in religious and educational retreats.
The church in Hamilton is called the Ancient Apostolic Catholic Church of the East (popularly known as Mart Shmooni Old Calendar Church). The sanctuary was purchased in 1988, the same year that the congregation was organized. This group is an offshoot of the Church of the East and adheres to the old church calendar, celebrating the birth of Christ on 7 January. The separation occurred in 1968 as a result of disagreements among the church hierarchy. The differences are administrative rather than doctrinal. The church had a membership of seventy families in 1994. The Jacobite Assyrians of Hamilton have their own church, the Mar Margus Syrian Orthodox Church, which is affiliated with churches of the same denomination in the United States.
The Assyrian church in London, also called the Holy Apostolic Catholic Assyrian Church of the East, was established in 1986 and had a membership of eighty-six families in 1994. The Chaldean Assyrians from Iraq and the Protestant Assyrians from Iran are comparatively fewer in numbers. They have established separate congregations in Toronto and worship in rented sanctuaries.