This has been identified as the Barksdale House, and is antebellum, as I had guessed.
This old landmark just keeps hanging on. I always look for it when I pass through Powelton.
I first photographed this historic church in early 2009. History regarding the congregation or structure is hard to come by, but Methodist archives indicate the present structure was built before 1863. This suggests that it was built before the Civil War, as little construction was going on at that time.
There is a bit more history at http://hrcga.org/powelton-methodist-hancock-5/
A scene in the 2009 movie Get Low (which starred Robert Duvall, Sissy Spacek and Bill Murray) was filmed in the historic church cemetery.
This church was organized in the mid-1780s and the present structure has been expanded around a construction of 1822. The Georgia Historical Commission marker, placed in 1956, reads: The Powelton Baptist Church, first known as Powell’s Creek Church, was constituted July 1st, 1786, with 26 members, by the Rev. Silas Mercer, the Rev. John Harvey and the Rev. John Thomas. The Rev. Jesse Mercer became pastor of this church on February 4, 1797, and served in that capacity until late in 1825. During his ministry, 200 persons were baptized into the church. The General Committee of the Georgia Baptists was organized here in 1803; the Baptist State Convention was formed in this church in 1822, and its sessions were held here in 1823 and in 1832.Governor William Rabun was a distinguished member of Powelton Baptist Church, and served it as a Clerk and Chorister.
Another important link to its history is found on a marble tablet placed on the grounds by the Georgia Baptist Convention in 1950: “In this church on this site the General Baptist Association of Georgia was organized June 27, 1822, by messengers from the Georgia and Ocmulgee Associations, and certain other Baptists, including Adiel Sherwood, whose motion in the Sarepta Association called for organization of the General Association. Jesse Mercer was elected president and Jabez P. Marshall was elected secretary. Adiel Sherwood preached the sermon, Luke 3:4. Name changed to The Baptist Convention of the State of Georgia in 1827.”