In 1835, a Presbyterian congregation had formed in Mainsville and part of the Spencerville charge and a church was constructed of log shortly after. Services were conducted by a pastor who also gave services at Spencerville and Cardinal. By the 1860s, the primitive log structure serving as the Presbyterian church was in need of upgrades or replacement. In 1865, the Raney family donated a portion of land on the northwest corner of the main intersection to hold a new Presbyterian church, which was to be called St James Presbyterian Church. In the late 1800s, the church separated from Spencerville to join the Cardinal charge; drive sheds were built behind the church for the congregation. The Presbyterian church closed in 1967 as membership declined and the building was converted into a home. Later into the settlement, in 1870, a Methodist church was built on land purchased from the Main family. This church drew large crowds to its early services however few residents became members; by 1878 the congregation consisted of 50 people. The Mainsville Methodist Church was demolished and replaced in 1893, with drive sheds being built to accompany the church. After the church union in 1925, the church became the Mainsville United Church until its closure in 1971. This church also became a private home.