While Protestant sects have contributed greatly to the state's history and development, more than half the state's population is Roman Catholic, a fact that has had a profound effect on Massachusetts politics and policies.
Both the Pilgrims, who landed on Plymouth Rock in 1620, and the Puritans, who formed the Massachusetts Bay Company in 1629, came to the land to escape harassment by the Church of England. These early communities were based on strict religious principles and forbade the practice of differing religions. Religious tolerance was included in the Charter of 1692, to protect the Baptists, Anglicans, and Catholics who had by then arrived in the colony.
The major influx of Roman Catholics came in the 1840s with the arrival of the Irish in Boston. By the 1850s, they had migrated to other towns and cities and formed the backbone of the state's industrial workforce. Later migration by Italian Catholics, German Catholics, and Eastern European Jews turned the state, by 1900, into a melting pot of religions and nationalities, although many of these minorities did not win substantial acceptance from the Protestant elite until the World War II era.
As of 2000, there were 3,092,296 Roman Catholics in Massachusetts, representing nearly half of the total population. The largest Protestant denominations were: the United Church of Christ, 121,826 adherents; the Episcopal Church, 98,963; the American Baptists (USA), 52,716,156; and the United Methodist Church, 64,028. The 2nd-largest religious affiliation is Judaism, with about 275,000 adherents in 2000. The Muslim population the same year was about 41,497 people. Though membership numbers were not available, reports noted that there were about 57 Buddhist congregations and 20 Hindu congregations throughout the state. About 35% of the population were not counted as members of any religious organization.
Although small, the Church of Christ, Scientist, is significant to Massachusetts's history. Its first house of worship was founded in 1879 in Boston by Mary Baker Eddy, who four years earlier had published the Christian Science textbook Science and Health with Key to the Scriptures. In Boston, the church continues to publish an influential newspaper, the Christian Science Monitor.