The Congregational Church known as “Independents” began as a Separatist movement from the Church of England after 1558. They rejected many Anglican practices, suffering greatly for their convictions. They believed in liberty of conscience, and the independence of each congregation. They first appeared in Ireland in 1646-7 and returned in force with Oliver Cromwell. English Separatists would be be the founders of New England for their own religious freedom (not anybody else’s).
In Ireland, they survived as a minor dissenting sect, and in 1695 there were six Independent congregations. They remained a small church, being depleted through emigration and death. This changed during the Ulster Revival of 1859, brought over from Scotland. At that time many congregations were founded. The Mother Church for all of Ireland is the Donegall Street Congregational Church in Belfast, even though other congregations are older. By 1901 there were 10,000 Congregationalists in Ireland.
Church registers can be sketchy with many registers surviving only from the 1880s. Others do start early, but have gaps. Other records have been disposed over the years. Still others in Ulster were destroyed in the World War II bombing raids. The Public Record Office of Northern Ireland (PRONI): www.proni.gov.uk houses many Congregational Church registers.
The earliest extant records for the Congregational Union of Ireland: www.cuofi.com date from 1829 to 1843. This archive of records has been inventoried in the PRONI online guide Introduction: Congregational Union of Ireland (2007). Other records include the denominational magazine The Irish Congregational Magazine (1861-76) with copies at the Linen Hall Library in Belfast: http://www.linenhall.com