[2][3] Thayer entered Harvard at an early age, but left after the first year and began to teach, at the same time studying divinity.
He was ordained in 1832, and from 1833 to 1845 was pastor of the 1st Universalist Society in Lowell, Massachusetts, where his ministry was important in the history of Universalism in New England.
During the crusade against Universalism from 1840 to 1842, he established and edited in its defense the Star of Bethlehem, and with his co-worker, Abel C. Thomas, wrote the Lowell Tracts in the same interest.
[4] Thayer was called to a pastorate in Brooklyn, New York, in 1845, where he edited the Golden Rule in the interest of the fraternity of Oddfellows.
In 1862 Thayer assumed the editorship of the Universalist Quarterly, which contains some of his most important literary work.