When several Episcopal families settled in Florida in the fall of 1877 the only place of public worship within twelve to fifteen miles was a log building east of Fort Mason and north of Lake Eustis Post Office. Here the Baptists and Methodists preached at irregular intervals. Because the nearest Episcopal priest was in Sanford, church services were rare and usually conducted by a lay reader.

That fall, the founding Episcopal families orgainized a Sunday School in a schoolhouse near Lake Swatara. When school trustees objected to the use of the building as a Sunday School, it was moved to Crooked Lake or Highlands School. The same families sponsored an interdenominational Sunday School which began in 1878. Church services were held occasionally with no set schedule. In January of 1882 the Bishop of Minnesota, who wintered in Maitland, visited the small group. From this group grew St. Thomas Church. The Rev. A.W. Knight Jr. was sent to take charge of the new mission. He held his first service on the first Sunday after Easter in 1882.

A lot at the corner of Lemon Avenue and Mary Street was donated for a church building and plans were acquired. The cornerstone was laid on November 26, 1882. It took several years to complete the interior. Churches in Pennsylvania and Massachusetts sent gifts of Bibles, prayer books, hymnals and a baptismal font. The Church was consecrated April 13,1890. St. Thomas is the oldest church building in Eustis and perhaps in Lake County.