Seybert was born 7 July 1791 in Manheim, Pennsylvania and died 4 January 1860 near Flat Rock, Ohio.
His father, Henry, had been a German mercenary soldier in the British army during the American Revolutionary War.
One year after Henry's death, John's mother deserted her sons and entered a religious community at Harmony, Pennsylvania, called the Rappites.
Though raised, even confirmed, a Lutheran, John was converted at a revival held by an itinerant Evangelical preacher, Matthias Betz, in Manheim, 21 June 1810.
In 1825 he was elected to the supervisory position of presiding elder, appointed to the Canaan District in Pennsylvania (a large area mostly east of the Susquehanna River, south into Virginia, and north into New York).
The expansion of the Evangelical Association, both in territory as well as the increasing complexity of its Charitable and Mission Societies, led the denomination in 1839 to adopt a great centralization of leadership.
As a bishop, Seybert was required to travel extensively throughout the expanding Church, both in general ministry as well as to preside at all Conferences.