In October 1877 after studying the New Testament, Johnson preached his first sermon and decided to dedicate his life to ministry.
While serving as the state evangelist in South Carolina, Johnson founded a popular Correspondence Bible School in 1886.
Johnson felt that he could better train the students at a resident school with the goal of training preachers, especially those who could not afford to pay for it, Johnson founded The School of the Evangelist in 1893 on farm land which had formerly been owned by his great grandfather along the French Broad River.
In 1891, Emma gave birth to a stillborn child and almost died herself during childbirth, and she was unable to have further children.
Johnson died during an operation in Baltimore, Maryland, on January 14, 1925, and was buried on the Heights on the college campus.