Thomas Finley Nelson was the sixth of ten children born to John Nelson and and his wife Elizabeth Pen(d)ley. On both sides of his family he descended from early settlers in the upper Yadkin River of Caldwell Co. He grew up on his father's farm. During the Civil War, Thomas served as a private in the 1st North Carolina Cavalry, attached to the Army of Northern Virginia.

Returning from the war, Thomas was called to the ministry. He studied at Wake Forest College and was ordained a minister of the gospel in the Baptist church. He served as pastor to several churches in Caldwell, Watauga and Wilkes Counties, while maintaining a farm in the upper Yadkin River valley near Patterson. In 1876 it was reported that "Rev. Thos F. Nelson of Watauga, has been turned out of the Baptist church for preaching the doctrines of the Advent church." [Caldwell Messenger (Lenoir, NC), Oct. 26, 1876, 3.] His strong preaching was often reported in the local papers.

On December 12, 1870 Thomas married Mary Elizabeth Greer (1853-1916) of Caldwell Co. The couple had eight children: Ada Virginia (b. 1872), Thomas Graves (b. 1873), Rose Lee (b. 1875), Horace Liman (b. 1877), William Milton (b. 1879), John Franklin (b. 1881), Samuel Hudson (b. 1883), and George Stanley (b. 1887).

By the mid-1880s Thomas was considering a move west. He made a trip to Kansas in 1885. In April 1886 he and his family joined a group of other Caldwell families in moving out to the Idaho Territory. He acquired a farm in Moscow, Idaho, and pastored the First (and only) Baptist Church. Opposition to the growing power of the Mormon Church led Thomas into politics. Barely two years after arriving in Idaho he was elected as a Democrat/Populist to the Territorial Council, the upper house of the legislature. When Idaho gained statehood in 1890, Thomas ran several times for the state senate and was successful twice (1897-98). In 1897 he failed in a close bid for election to the U.S. Senate.

Suffering from rheumatism and perhaps faced with a stalled political career, Thomas and his wife left Idaho for California in 1898. They settled on a fruit-growing ranch in the Pejaro Valley near Corralitos in the foothills of the Santa Cruz mountains. The last years of their lives were spent in Watsonville, CA in the home of their son William. Thomas died at the age of seventy, his wife following less than seven months later.