Nagyar, situated on the upper reaches of the Tisza, with the neighbouring Kisar, appears in our sources as early as the 14th century, first in 1374. In the 1400s, this area was granted to István Bátori, a country magistrate. The medieval parish church, the predecessor of the present church, was probably built after the donations of the Sigismund period, but its title is not known.

The eastern church stands at the centre of the settlement, on the axis of the widening main street.  According to the diocesan archives, the sacristy of the medieval church was demolished in 1642 and then renovated again in 1748, which Dean Kiss Kálmán, in 1877, described as a 'tasteless renovation', stating that 'the renovation has, however, completely stripped it of its original form'. In other words, it was then that the remaining medieval features of the building were removed. According to archival sources, in 1791 there was a tower next to the church, with a bell cast in 1733. Despite the renovations, the tower must have been in poor condition, as it was demolished a few years later and a tower was built between 1800 and 1802 on the west side of the existing church building, which still stands today. In 1836, a large and wide west wing was added to the rebuilt building and its straight-ended sanctuary was demolished. The church pulpit (1835), with its similar period fittings, and perhaps also the portico, with its enlarged windows, date from this rebuilding. On 11 April 1877, the church and the tower were again renovated, with new shingles being laid on the roofs. The ceiling was replaced in 1882, when the romantic ceiling painting, still visible today, was painted. The church had to be rebuilt in 1903. At this time the Art Nouveau helmet of the tower with a tin roof was made, and the windows of the church were also remodelled according to the church's treasury book. Between the two world wars, in 1934, the interior of the church was painted, and two years later, in 1936, Miklós Váradi, a master organ builder from the town of Váradi in rákospalota, completed the organ that is still in use today. After that, no major renovation work was carried out in the 20th century, and the roof was replaced with tin sheets in the 1960s.
At each end of the interior of the church there is a wooden choir set on Corinthian chaptered wooden columns. The parapet of the west aisle is the most ornate, with carvings of roses in the pilasters. The ceiling planking of the choir stalls is painted. The banded frames, painted on a light blue ground, are filled with a row of garlands drawn on a light yellow ground. The pulpit, dating from 1835, is a two-seater pulpit with a two-seater papyrus chair, in the vernacular tassel style, and its soundpost and parapet are richly decorated. The aisle and the sanctuary, which ends at the same height, are enclosed by a planked wooden ceiling. Geometric decorative elements were drawn in 1882 at regular intervals between the narrow bands of red, yellow, light brown, grey and black that run around the edges of the blue-painted ceiling. On the west side of the ceiling, a bible and chalice are depicted in an oval green leaf cluster, while on the east side, a musical score is painted in a green wreath, with instrument depictions behind it.
The church building was researched by architect György Szekér in 1990. It was then that the foundation walls of the straight-ended sanctuary, which predates the present-day sanctuary enclosure, were discovered, as well as a Gothic window on the south wall and a stone-framed doorway with eyebrow pediment. The only remains of the earliest painting of the church are the consecration crosses - one on the north and one on the south side. During the excavation, the wall paintings of the north nave wall were uncovered, which also covered the earlier consecration cross. The restoration of the mural cycle of the north wall was completed in 1992 under the supervision of the artist Peter Boromisza, a painter-restorer.
Unfortunately, the medieval mural on the north wall of the sanctuary is incomplete, having been partially damaged by a window opening made in the 19th century. The gaps between the frescoes have been filled with unpainted spoon-backed plaster. Although the mural is fragmentary, most of the depictions are still legible. The paintings are arranged in two bands and depict a cycle of 10 scenes from the Passion. The scenes beginning in the upper left corner are themed: above, the Entry into Jerusalem, the Last Supper, the next one, which was destroyed, is presumably Christ on the Mount of Olives. Next in sequence is the capture of Christ, Christ before Pilate. The bottom row shows the following scenes: the Mocking of Christ (Ecce homo), the Crucifixion (?), the Crucifixion, the Baptism of Christ and the Resurrection (?), which was destroyed. Small side scenes have been added to the top of some of the pictures.
Thus, according to our present knowledge, only the north and south nave walls of the medieval church without tower, which are now the walls of the sanctuary, have been preserved as a result of the repeated rebuilding of the church. Further research of the monumental church with its central tower facade could provide a definite answer to the question of what parts of the church are medieval, and some speculate that the entire church masonry, except for the tower, may have been preserved from the Middle Ages.

Nagyar, Reformed church (4922 Nagyar, Petőfi út, Hrsz.: 335): renovation of the roof (tin roofing, tile roofing, gutter renovation), renovation of the tower body (plastering, painting, window renovation), renovation of the nave, vestibule (plastering, painting), restoration of medieval frescoes and walls, environmental restoration (landscaping, replanting), renovation of the electrical system.