St Giles is a Presbyterian church. To find out more about the denomination please visit this link on the Presbyterian Church of Canada website.
The Presbyterian Church in Canada comprises four levels, or courts: Session (at the congregational level), Presbytery, Synod, and, since 1875, the General Assembly.
St Giles in Sarnia is part of Lambton-West Middlesex Presbytery. This Presbytery is part of the synod of Southwestern Ontario.