Isaac Thomas Hecker (1819-1888), American Catholic churchman, was the founder of the Congregation of Missionary Priests of St. Paul the Apostle, known as the Paulist Fathers.

Isaac Thomas Hecker was born on Dec. 18, 1819, in New York to German Protestant immigrants. After 6 years of schooling he went to work. The family was close, and Isaac's mother was an admirable woman who greatly influenced him. Hecker's thoughts increasingly turned to religion and theology, and in his quest he sojourned at two utopian colonies, Brook Farm and Fruitlands. His mentor was Orestes A. Brownson, a Catholic convert and social reformer.

In 1844 Hecker converted to Roman Catholicism. He soon became a priest in the Redemptorist order, which worked with German immigrants. Frustrated by the crippling regulations of this order and finally expelled from it, he founded a new order in 1858 with St. Paul as patron. Hecker served as superior general of the Paulists until his death in 1888. Although plagued by ill health, he displayed prodigious energy--planning, directing, writing, speaking, traveling--all in the hope that the Roman Catholic Church might find itself at home in America and that increasing numbers of Americans might find their spiritual home in Catholicism.

Though the Paulists remained small in number, their influence was great. Hecker was not a rebel, but he held that a rigid authoritarianism would blight the development of Christian perfection. The Paulists demanded no vows of its members, shifting emphasis from rules to conscience and the guidance of the Holy Spirit. Hecker was convinced that the Church would prosper in the free environment of the United States and that the way to make Catholicism attractive to Protestants was by infusing it with the "American" spirit. He won converts by emphasizing partial agreement and inviting Protestants to inspect the virtues of the True Church, and by not denouncing all Protestants as heretics. A confirmed humanitarian, Hecker understood that the Church must serve man's needs and that Catholicism would spread to the degree that the Church's deeds matched its creeds.

Hecker was angrily denounced by conservative churchmen both in America and abroad. After his death the controversy over what some termed the heresy of "Americanism" (sparked in part by the French translation of an 1891 biography of Hecker) resulted in the condemnatory papal letter Testem benevolentiae (1899).