Allen's master was impressed with his deep piety, and permitted him to conduct religious services in his home, was himself converted at one of the meetings, and made it possible for Allen and his family to obtain their freedom. Allen educated himself by private study. While working at such occupations as wood-cutting and hauling he embraced every opportunity for preaching to both whites and blacks. He traveled through various parts of Delaware, New Jersey, Pennsylvania, and Maryland; and at the meeting of the first general conference of the Methodist Church in Baltimore, in 1784, was accepted by that hierarchy as a minister of promise. He then traveled with Richard Watcoat and Bishop Asbury, who gave him appointments to preach. Coming to Philadelphia in 1786, he was asked to preach occasionally at the St. George Methodist Church. He began also to conduct prayer-meetings among his own people. He immediately thought of making a special appeal to the Negroes by establishing for them a separate place of worship, but both the whites and the blacks objected. When, however, the forceful preaching of Allen attracted to the church a large number of Negroes, the white members objected to their presence, pulled them from their knees one Sunday when in an attitude of prayer, and ordered them to the gallery. Rather than submit to the insult, the Negroes withdrew and established in 1787 an independent organization known as the "Free African Society. "
Out of this body some few went with Absalom Jones to establish the African Protestant Episcopal Church, but Allen influenced the majority to organize an independent Methodist church. The church thus founded was dedicated by Bishop Asbury in 1794. Allen was ordained deacon in 1799, and elder in 1816. In the meantime, other Negro churches, separated from the whites in the same way in New York, New Jersey, Delaware, and Maryland, offered the opportunity for national organization. This was effected by sixteen congregations in 1816, and Allen was chosen bishop. Thus began the African Methodist Episcopal Church, which is one of the strongest organizations ever effected by Negroes.
Allen labored incessantly for the promotion of this cause until he died in 1831. By that time he had finally succeeded in impressing the public and had won national standing for his denomination. It was not allowed to expand in the South after the supposed connection of certain of its members with the Denmark Vesey plot in Charleston, South Carolina, in 1822; but the work had found its way into the Northern states east of the Mississippi River. In 1836, five years after Allen's death, the churches numbered eighty-six. There were four conferences, two bishops, and twenty-seven ministers. These served 7, 594 members, and controlled $125, 000 worth of property.
Allen early manifested interest in religion while reaching manhood at the time of the increasing toleration and religious liberty granted such sects as the Quakers, Presbyterians, Methodists, and Baptists. He was converted under the influence of the Methodists.
Allen was married twice: first he married Flora in 1790; then, in 1802, he married
Sarah Bass. He had three children.