The Oak Grove Union church was built in 1895 on the property belonging to Mr. J. W. Reynolds. Mr. Reynolds and the men in the community built the church which represented different denominations. The denominations were Cumberland Presbyterian, Methodist Episcopal Church South, The United Baptist, and the General Baptist. The church served all four denominations until the early 1920s. Oak Grove Union church is located 6.5 miles south of clay, KY on Highway 132.
On record at the library at Bethel College, the year of 1898 and 1899, J. W. Reynolds and S. W. Mayes served as Clerk of the Session; therefore, they would have been Elders of the church.
The first twenty years of records were destroyed in a fire at the home of one of the members. There is no complete record of charter members; the following were among the charter members: J. W. Reynolds, America Hazel Reynolds, Nora Reynolds Brantley, S. W. Mayes, F. E. Lofton, E. A. Prow, and J. B. Brinkley.
In 1922, the church had some major repairs due to damage caused by a storm. In 1956, the church had another major remodeling with a porch added. In 1987, a new carpet was installed and a picnic area with a shelter and tables was built. In 1989, new church pews were purchased. In 1991, four new Sunday School classrooms and a nursery were added. In 2004, a much larger fellowship room was added to the church and new carpet installed, along with eight beautiful stained glass windows.
Oak Grove Union celebrated its 100th birthday with a special service in 1995. Rev. Dale Williams was the pastor at that time.
Oak Grove CP Church has enjoyed the ministry and prospered under the following ministers who have served the church: Rev. W. W. Wynn, 1898-1899; Rev. J. R. King, 1900-1902, 1903-1908, 1923-1925; Rev. J. B. Lowery, 1909-1911; Rev. D. W. D. Moore, 1912; Rev. O. D. Spence, 1913-1915; Rev. C. T. Boucher, 1916-1919, 1939; Rev. V. L. Stone, 1921; Rev. Harve Vanhoosier, 1922; Rev. Lacy Baird, 1926-1928; Wallace Rutherford, 1938; Rev. A. R. Poole, 1944-1945, 1958-1906; Rev. Ed Glover, 1946; Rev. R. T. Mitchell, 1947; Rev. Ray Wigginton, 1948; Rev. Morris Clark, 1953-195; Wendell Ordway, 1956-1957 (candidate; Rev. Dale Shelton, 1962-1964; Rev. Joe Pat Thornton, 1965; Calvin Mouser, 1966; Percy Brandon, 1967 & 1973; J. C. Womack, 1968; James Fulton, 1969-1970, 1977, & 2006; Charles Westfall, 1976 & 1978; Wm. H. Perkins, 1979-1980; Ray Latham, 1981-1983; Rev. Paul Stone, 1983-1992; Ronnie Cowan (candidate); 1992-1994; Rev. Dale Williams, 1995-2005.