Watertown, first known as the Saltonstall Plantation, was one of the earliest Massachusetts Bay Colony settlements. John Winthrop, governor of Massachusetts Bay Colony, led the first wave of Puritans across the Atlantic to the New World. With him on the ship was Rev. George Phillips. Watertown was begun in 1630 by a group of English settlers led by Sir Richard Saltonstall and Rev. Phillips, and was officially incorporated that same year. Although Rev. Phillips was one of the influential shapers of New England Congregationalism, he was controversial among his Boston brethren.

During the colonial period, Waltham was part of Watertown and there was just one meetinghouse located in East Watertown, now a part of Cambridge. What we know as Waltham today was the farming district of Watertown at the time, and the people who lived and worked here found it burdensome to travel all the way to East Watertown for religious services, political meetings, and social functions, all of which took place at the town meetinghouse. First Parish in Waltham resulted from the efforts of the people who lived in what would become Waltham to have a meetinghouse closer to home. Waltham was first settled in 1634 as part of Watertown and was officially incorporated as a separate town in 1738.

The church gathered in 1630 and changed to the Unitarian denomination in the 19th century. In 1855 a group of orthodox Trinitarian Christians set out and founded a new church in Watertown, naming it the Philips Congregational Church in honor of their spiritual forefather, George Phillips. The Phillips Congregational Church merged with another congregation in the early 2000s and is now Redeemer Fellowship Church.