The Orthodox tradition in Kostomłoty has started in the first half of the 17th century and is connected to the icon of St. Nikita, dated back on September, 4, 1631. In the interwar period, in 1927 there was conducted an experiment by the administrative authorities to reestablish the Union – the so-called Neo-Union. In that way Orthodox church together with the icon of St. Nikita as well as the parish house were taken by the Catholic Church and has started functioning as the Neo-Union parish. The Orthodox adherents established the church in one of their houses, which was demolished in 1938 as a result of an action to destroy Orthodox churches. The Second World War and actions with the aim to expel Orthodox people influenced the adherents negatively. Those who left in Kostomłoty have been going to churches in Kodeń or Terespol. In 2003, as a result of requests of local Orthodox people, there was bought a building and the wooden church from Dobrowoda village, Białystok region, was transported to Kostomłoty. That church with time became the sanctuary for the icon of the Mother of God of Iwiersk – a gift from monks from St. Mount Athos and for the icon of St. Seraphim of Sarov. The iconostasis and icons were made by Mirosław Trochanowski, graduate of Post-secondary School of Iconography in Bielsk Podlaski. There are also other icons written by graduates of the Iconography School and icon of the Mother of God of Iwiersk, which was brought from St. Mount Athos. St. Seraphim of Sarov Monastery in Kostomłoty was established on August, 15, 2003, based on the decision of Abel, Archbishop of Lublin-Chełm Diocese. Priest igumen Ambroży (Adam Godun) was appointed as a head of the monastery. On November, 23, 2003 the cornerstone was set under the church of St. Seraphim of Sarov. The building of the church was transported from Dobrowoda village (Podlaskie voivodeship). The first liturgy was celebrated on the Day of the Nativity of Christ in January 2004. In the same year, on May, 3, the church was consecrated by Metropolitan Sawa and Archbishop Abel.