Thomas Williams (1847–1913) was a Welsh Christadelphian who emigrated to America in 1872, and eventually became editor of The Christadelphian Advocate magazine and author of The Great Salvation and The World's Redemption, reserving him a place alongside Christadelphian founders Dr. John Thomas and Robert Roberts. When his appeals to English brethren went unheeded, he became the most prominent of the brethren who avoided these divisive factions, and later became known as Unamended Christadelphians because they never adopted a particular amendment to the Christadelphian statement of faith.
Williams was born on April 7, probably in Parkmill, near Swansea. Having apprenticed as a carpenter in Parkmill, he then found work with a William Clement, later his father-in-law, a member of the Christadelphian Ecclesia in Mumbles, and was immersed on Sunday January 15, 1868. He married Elizabeth Clement and the couple had eight children - Clement, William, Katherine, in Wales, and Gershom, Fred, May, George and Bessie in America.
In 1872 he moved from Wales to Riverside, Iowa where he worked as a carpenter and joined the local "ecclesia" of 12 members In March 1885 he commenced publication of The Christadelphian Advocate Magazine at Waterloo, Iowa. In 1888 he met Robert Roberts in Wauconda, Illinois and again in Lanesville, Virginia for the first time since leaving Wales. In 1891 Williams began to publish a second magazine, The Truth Gleaner aimed at non-Christadelphians, and in 1892 relocated to Chicago. In 1893, in response to the expected visitors to Chicago for the World's Columbian Exposition, Williams published 10,000 copies of the booklet The Great Salvation. By 1972 105,000 copies had been published. In 1905 J.G. Miller of Waterloo, Iowa translated the booklet as Die grosse Erlösung.
Williams was also active traveling throughout North America as a preacher and Christadelphian speaker. As was typical of religious speakers of the period Williams participated in lengthy public debates with other religious groups.