Historical outline
The origins of the parish in Mosciski are not entirely clear in terms of dating. In the first centuries of its existence, the parish belonged to the Przemyśl deanery, but in 1641 a separate deanery was created, which included as many as fifteen neighbouring villages. The first wooden church burned down during the Turkish-Volga invasion in 1498, and another, also wooden, incarnation survived until the early 17th century. It was then that the decision was taken to build the brick building in question. It was consecrated two years before the construction was completed, which was closed in 1606. Unfortunately, during the Khmelnytsky uprising, the temple was looted and destroyed by Cossacks. Paradoxically, not much information has survived to our times about what happened to the church in the following centuries. Among other things, it is known that a new organ was consecrated in 1883. A thorough renovation was carried out in 1904, when the parish priest, Father Alfred Białogłowski, initiated the construction of a new presbytery, the reconstruction of the great altar and the conservation of such elements as the pulpit, organ and other altars. A stone fence was also made around the building, which surrounds it to this day. Unfortunately, the First World War brought some damage and the confiscation of the bells in 1916.

The inter-war period brought further minor repairs, maintenance and care of the building. Interestingly, it did not suffer any damage during the Second World War and, even more interestingly, was not closed by the Soviets after the conflict, which was not at all the rule in those days and in those parts. In 1989, the congregation of the Little Sisters of the Immaculate Heart of Mary (honoratas) joined the parish. The church celebrated its 420th anniversary in 2024. Currently, the following villages come under the territory of the parish: Stronghold, Zakosciele, Hodynie, Cherniawa, Meleszkow, Malnov, Malnovska Volya, Gostincev, Arlamovska Volya, Sokola, Chorosnica, Slomianka, Berehowe, Vojkovice, Wierzbowce, Okno, Tzuculowce-Вільхівці, Voronov, Glushkov, Horodnica, Przeodziewanie, Dubki, Daleshovo, Repuzhaniece, Kolanki, Korzeniow, Kunisovce, Unish, Kopaczynce, Luka, Monastyrek, Michalcze, Bilka, Nezviska, Olejewo-Korolejówka, Roginia, Potoshchyce, Semyakovce, Serafińce, Soroki, Slobodka, Strzelce, Probabyn, Tyszkowce, Vladypol, Novosiolka, Toporovce, Targovitsa, Cherniatyn, Chortovets, Chernelitsa, Khmelovka, Yakubovka, Jasienov-Pilny.

Architecture
The brick, plastered building is situated on the edge of the old town and surrounded by a wall dating back to the early 20th century. The church is oriented (i.e. facing towards the symbolic east, by implication Jerusalem) and consists of a three-nave and three-bay basilica-style body and a two-bay chancel, which is slightly lower than the main part. Adjacent to the central bay of the south nave is a rectangular porch. A rectangular but closed trilateral chapel of Our Lady of Czestochowa is located at the east bay of the north nave. Next to it, a rectangular sacristy is located next to the presbytery.

The nave communicates with the side aisles through semicircular arcades. The massive rainbow arcade with a slightly pointed arch draws attention. The interior elevations are notable for their lack of articulation, but have a rather rich painting decoration. A cross-ribbed vault is used in the presbytery and a grid vault in the nave. The side aisles and the sacristy have barrel vaults with lunettes. The porch was covered with a cross vault and the chapel of the Virgin Mary with a multi-panelled vault with brackets decorated with floral motifs. In the other interiors, ceilings were chosen.

The choir is made of brick, supported by two square pillars and two half-pillars embedded in the wall. Access to the choir is via a brick staircase located in the north-west corner of the church under which there is a small storeroom.

As Marek Walczak writes in his study of the building, the façade of the church reflects the spatial layout of the body, i.e. it is tripartite. It is single-storey with a triangular gable, separated by a prominent cornice, which is extended through the whole part of the main body to the presbytery. The most significant decorative element of the façade are the pinnacles that wander towards the gable and open up the nave section. When the nave ends, there is exactly the same architectural treatment, which fastens the main part together with a kind of buckle. The articulation of the nave and chancel, on the other hand, is carried out in the same way. The facades of these two sections are framed by buttresses on the boundaries of the bays.

All the windows in the church are rectangular, closed with a slightly pointed arch and embayed on both sides.

The nave, chancel and porch are covered by gable roofs. Above the side aisles and the sacristy, pent roofs were used. A multi-pitched roof was placed over the chapel of Our Lady of Czestochowa, as well as over the apse. All the roofs are covered with sheet metal. The turret is made of brick.

The most important elements of the church furnishings and surroundings include:

• Neo-Gothic main altar, probably dating to the early 20th century;
• A richly decorated neo-Gothic altarpiece from the 19th century, filled with motifs and biblical figures. Sculptures include "Saint John the Baptist", "Zechariah and Saint Elizabeth", "Christ and the angels", "Saint Peter and Saint Paul";
• Altarpiece to the Sacred Heart of Jesus in neo-Gothic style (dated early 20th century);
• Altar of the Virgin Mary at the rainbow arch;
• Neo-Gothic altar of St Anthony (dated early 20th century);
• Holy Trinity altar;
• Altar of Our Lady (neo-Gothic, dated early 20th century);
• Neo-Gothic pulpit dating from the early 20th century;
• Bell tower located in the south-eastern part of the church grounds, and containing three bells, two of which date from the 1930s, but one (weighing 202 kg) dates from 1550.