The researchers claim that during the pre-Christian period, the religion of the inhabitants of Silesia was analogous to the beliefs of other Slavic tribes. In the valley of the Upper Odra river, the most important place of worship was probably a place presently known as St. Anne’s Mountain, whereas the most important center of worship in Silesia was located on the Ślęża Mountain, the name of which, as well as the name Śląsk (Silesia), share the same Slavonic etymology – the word “śląg,” which some researchers believe to mean moisture; however other researchers state that it is a Silesian adaptation of the word “szlag,” which means lightning. According to the Eastern Slavic sources, the first person who undertook the task of introducing Christianity to Silesia was Osław, a student of the Slavic apostles, Cyril and Methodius, residing in Nitra (Slovakia). In 863, he supposedly arrived in Silesia, which at that time was a province of the Great Moravian Empire, and baptized many of its inhabitants in the Eastern Orthodox rite. The traces of his activity were preserved in an oral tradition in Opole, Koźle, and Racibórz. However, the permanent effects were brought only by the Christianization in the Roman Rite conducted within the territory of the country of Mieszko I after the year 966.
The first church in Koźle, like the majority of Silesian churches in the early Middle Ages, was made of wood. The first written mention of the existence of the Koźle parish that we are aware of comes from 22 January 1293. On this date, Kazimierz II, Duke of Koźle and Bytom, renounced his right to tithes from the Łężce, Pokrzywnica, and Cisowa villages for the parish in Koźle. It can be assumed that at that time, the parson of the Koźle parish was the superior of a local commandery of Johannites, who were brought to Koźle by the Piasts of Opole and remained in the town until the secularization of the order in 1810.
In the first half of the 15th century, Koźle was visited by Franciscans, who built their monastery and St. Barbara’s Church in the region of Rybarze. These buildings were destroyed in the 17th century, and it was not until the 18th century that the Franciscans returned to Koźle, where they built a monastery and an adjacent church at the street presently known as ul. Czerwińskiego. The Franciscans banished from Silesia in 1810 did not return to Koźle.
During the 16th century, Protestants appeared in Koźle and prayed in private houses. The Protestant temple was built only after Silesia was conquered by Prussia in the 18th century. It was demolished after World War II. It was also during the 18th century when Jews were allowed to settle in Koźle, and, at the end of the 19th century, built an impressive synagogue there. Unfortunately, it was burned down by the fascist military group during the Night of Broken Glass on 9 November 1938.