 When the nation underwent the Scottish Reformation in the 16th century, St Rufus changed from being a Roman Catholic church to become a part of the Church of Scotland, of which the current church is still a constituent.In 1609, the Keith Old Bridge across the River Isla was built on the north side of the original church.The church was described by 19th-century chronicles as "a capacious, though not very commodious building" and "a large awkward incommodious building" with low buttressed walls and an equal number of windows and doors.