The medieval parish church of Carei was dedicated to the All Saints during the Middle Ages. It was used by the Calvinist community in the 16th century, until 1723, when it was given to the Catholics by Sándor Károlyi (1668–1743). In compensation, the Count built a new church for the Calvinists, at the border of the town. Sándor Károlyi invited to serve in the church the Piarist Order, and he built a monastery and a school, which started to function in 1727. A drawing from the 18th century shows that the church kept its medieval structure at that time, in resemblance with other known edifices of the 15th century in the region: polygonal sanctuary, buttresses, and a tower on the western façade. At that time, the tower had a Baroque steeple, shaped like an onion dome. A new church was built by Antal Károlyi (1732–1791) in Baroque style, in order to express his gratitude for the birth of his son, Joseph. The construction work started in 1769 and lasted until 1791. The project was made by the architect of the Károlyi family: Joseph Bitthauser. In the Historia Domus, the name of Franz Siebel is also mentioned, in connection to the construction works. The church is one of the most representative Baroque buildings of this region. The nave has a rectangular ground plan, with rounded corners, enlarged with a smaller semicircular sanctuary, and a similar porch. There are sacristies on the both sides of the sanctuary with oratories on the upper level. In the porch a gallery was built for the organ, with composed capitals and curved parapet. The tower has two small side porches and staircases. The interior is monumental, the space is lighted and it is organized with the combination of the longitudinal and central arrangement. The walls are divided with pilasters, and niches are opened for eight side altars.
Six of the side altar-paintings are of high quality, made by the Viennese master Johann Ignatz Cymbal in Baroque style. They represent: St. Andrew Avellino, St. Joseph, St. Anthony of Padua, St. John Nepomuk, Holy Trinity, Holy Virgin of Hungary, and the three St. Kings of Hungary. The spherical vault of the nave is decorated with stuccoes.
The main altar is built of gray marble with pilasters from rose-marble with delicate veining, and composed capitals. The whole construction is dominated by the altar painting, which represents the patron saint of the church, St. Joseph of Calasanctius, the founder of the Piarist Order. It is particular that the people who are listening to the sermon of the saint are depicted in Hungarian noble cloths. The table of the altar has the form of a sarcophagus, the white and golden tabernacle is put on the top of it, in the middle of two adoring angel. The door of the tabernacle is decorated with a bas-relief representing the Crucifixion. The altar is completed on the top, over the entablature and on the vault, with a stucco decoration, representing angels offering a crown for the patron saint and putties with garlands. The baroque forms dominate the exterior of the church: the main façade is decorated with statues, and prominent cornices and pilasters. The tower is in the front of the main façade, and it has a curved contour. On the upper level, and on the side-façades of the tower the traces of the restoration work of Miklós Ybl can be observed, made after the earthquake of 1834. On the cornice four-four stone-statues are put on the each side of the church, held by volutes, while on the third level of the tower is the monumental coat-of-arm of the Károlyi family. The roof is mansard, a rare technical solution for a church. (TSz).
The medieval parish church of Carei was dedicated to the All Saints during the Middle Ages. It was used by the Calvinist community in the 16th century, until 1723, when it was given to the Catholics by Sándor Károlyi (1668–1743). In compensation, the Count built a new church for the Calvinists, at the border of the town. Sándor Károlyi invited to serve in the church the Piarist Order, and he built a monastery and a school, which started to function in 1727. A drawing from the 18th century shows that the church kept its medieval structure at that time, in resemblance with other known edifices of the 15th century in the region: polygonal sanctuary, buttresses, and a tower on the western façade. At that time, the tower had a Baroque steeple, shaped like an onion dome. A new church was built by Antal Károlyi (1732–1791) in Baroque style, in order to express his gratitude for the birth of his son, Joseph. The construction work started in 1769 and lasted until 1791. The project was made by the architect of the Károlyi family: Joseph Bitthauser. In the Historia Domus, the name of Franz Siebel is also mentioned, in connection to the construction works. The church is one of the most representative Baroque buildings of this region. The nave has a rectangular ground plan, with rounded corners, enlarged with a smaller semicircular sanctuary, and a similar porch. There are sacristies on the both sides of the sanctuary with oratories on the upper level. In the porch a gallery was built for the organ, with composed capitals and curved parapet. The tower has two small side porches and staircases. The interior is monumental, the space is lighted and it is organized with the combination of the longitudinal and central arrangement. The walls are divided with pilasters, and niches are opened for eight side altars.
Six of the side altar-paintings are of high quality, made by the Viennese master Johann Ignatz Cymbal in Baroque style. They represent: St. Andrew Avellino, St. Joseph, St. Anthony of Padua, St. John Nepomuk, Holy Trinity, Holy Virgin of Hungary, and the three St. Kings of Hungary. The spherical vault of the nave is decorated with stuccoes. 
The main altar is built of gray marble with pilasters from rose-marble with delicate veining, and composed capitals. The whole construction is dominated by the altar painting, which represents the patron saint of the church, St. Joseph of Calasanctius, the founder of the Piarist Order. It is particular that the people who are listening to the sermon of the saint are depicted in Hungarian noble cloths. The table of the altar has the form of a sarcophagus, the white and golden tabernacle is put on the top of it, in the middle of two adoring angel. The door of the tabernacle is decorated with a bas-relief representing the Crucifixion. The altar is completed on the top, over the entablature and on the vault, with a stucco decoration, representing angels offering a crown for the patron saint and putties with garlands. The baroque forms dominate the exterior of the church: the main façade is decorated with statues, and prominent cornices and pilasters. The tower is in the front of the main façade, and it has a curved contour. On the upper level, and on the side-façades of the tower the traces of the restoration work of Miklós Ybl can be observed, made after the earthquake of 1834. On the cornice four-four stone-statues are put on the each side of the church, held by volutes, while on the third level of the tower is the monumental coat-of-arm of the Károlyi family. The roof is mansard, a rare technical solution for a church. (TSz).