The near-border position, tempestuous past and social state of flux led diverse religions to mutually imbue, complement and exist on the territory of Kozarska Dubica. Nowadays, Dubica is adorned with many religious buildings and cultural structures, dedicated to Islam, Roman Catholicism and Eastern Orthodoxy.
In the tranquility of the woodlands of Kozara, next to the stream Moštanica, some 12 km to the South from the center of Kozarska Dubica there is the famous Moštanica Monastery, one of the most beautiful and most significant monasteries of the Serbian Orthodox Church in BiH. There is no precise data on the founding of the monastery, its financers or the builders of its harmonious and rich architecture. Numerous legends point to at least a five-hundred-year old presence as the spiritual and religious center of the Kozara area. The first written records of the Moštanica Monastery date back to 1579.. It is assumed that it was reconstructed some time prior to that year, during the Patriarchate of Macarius, cousin of the Grand Vizier Mehmed-Pasha Sokolović. Situated on the border between the two empires, its destiny was one of hardship – eight times burned and looted, but subsequently reconstructed and restored. In recent times, next to the monastery, a mansion and a smaller chapel with a bell-tower have been built. The monastery is visited my numerous tourists throughout the year. Each year on 19. August there is a celebration of the Transfiguration of the Lord, as well as the “Ojkača Evenings”, a competition of traditional popular singing. Next to the monastery, there are traditional picnic spots for locals and their guests and vast meadows interlaced with Moštanica stream.
In the vicinity of the Monastery, in the late 18th Century, was born St Deacon Avacum, who took his priesthood there. Given the historic circumstances and following the Hadži-Prodan’s Revolt in 1814., he ended up in the Nebojša Tower in Belgrade, among other imprisoned Serbs being offered to convert to Islam and thereby save their lives. Epic popular songs sing about Avacum’s continuous denial and loud singing while on his way to Stambol Gate, the location where the executions took place. Since 2006., 30. December, the Day of Blessed St. Avacum, Deacon and the Martyr, is celebrated as the Day of Municipal Patron Saint.
In the near vicinity of the Monastery, there is a graveyard with a monument to and the grave of Petar Popović Pecija (1830.–1875.), a famous brigand and freedom fighter, who was killed during the so-called Uprising in BiH.