The date of the erection of the first church is unknown. According to some German documents belonging to the Plainfield Reformed Church,in 1747 the Reformed congregation authorized Adam Dietz to secure some land on which they planned to erect a church. This tract of land was secured in 1750 but the records do not indicate the location of this church. Tradition says that the church stood across the street from the south side of the graveyard. Later in 1790 a second parcel of ground (60 acres) was bought from Casper Doll. A small log church was erected for a small congregation on the first tract of land in 1770. "The Ministers of the German Reformed Congregations in Pennsylvania and other Colonies in the 18th Century" - William. Hinke, page 188, reads: "In August, 1782, a German traveler, John David Schopf, visited some of the settlements, near Wind Gap, and writes as follows: 'We passed a small log church which has been built by the Lutherans and the German Reforms, whom it serves alternately as a place of worship'." This quotation informs us that the Reformed and Lutheran people erected the first log church in 1770. As the congregations grew, they resolved to enlarge and renovate the log church. The renovations were done with subscriptions made by members of the two congregations. Among the contributors we find the name of Adam Andre and John Miller who later were the Treasurers of the Lutheran congregation. Since the Lutheran congregation worshipped in the Reformed Church prior to 1800, they were pleased to have a part in sharing the cost of the "renovated" church even though they apparently had no legal interest in the property.
Information leads us to believe that the parochial schoolhouse was used as a place of worship up to 1770. According to the "History of the Plainfield Church," by Pastor Brong, published in 1909, this church of 1800, "the renovated church" stood across the street from our present building where the place is marked by an offset in the stone wall which is built along the west side of the graveyard. There is a marker designating the possible site.
Years later the Lutherans were given an equity in the Plainfield Church property. According to the deed of November 19, 1831, the Reformed Congregation conveyed to Frederick and Elizabeth Germantown 11 acres and 159 perches of land. On the same day, Mr. and Mrs. Germantown deeded to the trustees of the Reformed and Lutheran Congregations this same tract of land "for the purpose of erecting and building thereon a church jointly for the two congregations . . ."
In 1832, a union church was erected by the two congregations which served as a place of worship until 1916. Also in 1832, the log church of 1805 was sold and moved to Wind Gap-Belfast Road which later became the farm house on property owned by Margaret Berger.
Up to 1833, the Reformed and Lutheran congregations worshipped without the use of an organ. The singing at times had been led by a person called "a foresinger." Frequently these duties were assumed by the catechist, until the election of the first organist in 1833. St. Peter's first organ was the Dannaker Organ which was purchased from the Reformed Church in Easton for $670.00. (See History of St. Peter's Organs)
The third church was built by both congregations as a union church in 1832 at a cost of $6,000. This church was built of brick which was made on the farm of Frederick Germantown during the pastorates of Revs. Pomp and Probst. The cornerstone was laid on June 11, 1832 with appropriate services held by both pastors of both denominations. The two congregations adopted twelve joint rules to govern their mutual church property. These unaltered rules guided the management of the two congregations for many years. Amended rules were adopted October 5, 1916, just before the new granite church was erected.
On April 10, 1914, at a joint meeting of the Lutheran and Reformed congregations, it was decided to build a new church. The plans of the architect, George E. Savage, of Philadelphia were approved and adopted on May 30, 1914. The contract was awarded to John Stiles on July 1, 1916, and it was decided the church would be built of brick. However, a short time later the contract was changed to Holmesburg Granite. On October 29, 1916, the cornerstone was laid for St. Peter's Union Church. On June 9, 1918, the Sunday School Chapel was dedicated, and on August 10 of the following year, the church was dedicated. The social room was constructed at a later date and dedicated May 22, 1938.
On September 1, 1926, Rev. Luther B. Klick became pastor of the Plainfield Lutheran Parish. He served this parish for 32 years until his death in 1958. During his ministry, the church held a service for the burning of the last Mortgage Bonds and a Baptismal Font was dedicated in October, 1928.
Other changes also took place in the Plainfield Parish. In 1958, the 4-charge Plainfield Parish, consisting of Grace-Belfast, Trinity-Wind Gap, Jehovah-Bushkill Center, and St. Peter's-Plainfield was re-aligned. The former two churches became the Belfast-Wind Gap Parish, and the latter two formed the Plainfield Parish.
In 1959 Rev. John C. B. Robinholt became pastor of the Plainfield Parish. About that time, a decision was made to have a parking lot for the church members. Church sheds which were built in the 1900's to shelter horses had to be purchased from the owners so that we could be torn down to build a parking lot next to the church.
Rev. Robinholt left in 1966 to become pastor of Christ Lutheran Church in Dryville, Pennsylvania. During his last year, there were many discussions with the Reformed congregation regarding their desire to have their own church building.
The Union Church was used regularly by the Reformeds and Lutherans until the congregation finally decided to dissolve their present arrangement in June, 1967 when Rev. Forrest P. Miller was pastor of the Reformed congregation and Rev. Sterling R. Geiger was pastor of the Lutheran congregation. On December 10, 1967, the Articles of Agreement were signed with the understanding that the Lutheran congregation would pay $58,000 to the Reformed congregation.
Again there was talk of dissolution, this time between the two churches comprising the Plainfield Parish - Jehovah-Bushkill Center and St. Peter's-Plainfield. In June 1970, the members voted at St. Peter's to dissolve this relationship and St. Peter's became a single parish with Reverend Geiger remaining as pastor.
In 1975, stone masons sand-blasted the granite walls and rejointed cracked areas of the building. The stained glass windows were repaired. A few years later, storm windows were installed, the interior of the church was painted and new carpet was installed in the church area, new bathrooms were installed upstairs and a new roof was put on the Sunday School area.