Originally known as the Union Church, the old stone structure is the third church constructed by the early European settlers in Long Valley. These settlers came from what we now call Germany – in the area of the Rheinish Palatinate. Both Dutch Reformed and German Lutherans were among the early settlers. Union Churches were used by two denominations. In 1743-1745, the new settlers built a crude log chapel south of current Long Valley at the foot of Fox Hill. Henry Melchior Muhlenberg, noted as the father of Lutheranism in America, preached at the log chapel in August 1745.

Eventually, there was a split among the Dutch Reform settlers. Some remained south of town (this is now the Fairmount Church). The other branch of the Dutch Reformed and the German Lutherans built a new log chapel in 1747 in Long Valley (then called German Valley). In 1774, this stone church was built, probably on land adjacent to the old log church. During the colonial days, the Union Church was served by preachers from New Germantown (now called Oldwick) or by lay preachers. Henry Melchior Muhlenberg preached at the log church here in Long Valley, as did his sons, John Peter Muhlenberg and Gotthilf Heinrich Ernst Muhlenberg. In 1771, John Peter left the Zion pastorate (Oldwick and Long Valley) to serve a congregation in Virginia. It is from his pulpit in Virginia in 1776 that John Peter preached a sermon based on the text from Ecclesiastes- “A season to every purpose under heaven”. He declared there was a time to preach and a time to fight. The next day he took up a commission in the Revolutionary forces.