Stillwater United Church, formerly known as Second Baptist Church, is a historic church at 135 Hudson Avenue in Stillwater, Saratoga County, New York. It was designed by architect Marcus F. Cummings and built in 1873. It has a rectangular, gable roofed sanctuary above a raised basement of cut limestone blocks in an early Romanesque or Northern Italianate style. It features an engaged brick bell tower culminating in a belfry and topped by a tall spire. A two-story brick education wing was added in 1952. It was listed on the National Register of Historic Places in 2006.