	He was one of the main proponents of Bosniak nationhood, and he fiercely advocated against imminent "Croatization" of Bosnian Catholics on one side, as well as imminent "Serbianization" of Bosnian Orthodox people on the other, as he called them Catholic Bosniaks and Orthodox Bosniaks in his work. His position and doctrine was that all Bosnians or Bosniaks are one people of three faiths, and that up to late 19th century, no Croats and Serbs lived in Bosnia and Herzegovina. Although Fra Antun Knežević was not a unique phenomenon in this sense, he was certainly among most articulate. He had strongest impact, along with fra. Ivan Franjo Jukić from whom he took the idea, and who was his teacher and mentor earlier in his life. Since 17th century many other members of Franciscan order in Bosnia accepted the idea of a Bosniak identity, nurturing it within the brotherhood and carried it over into 18th and 19th century. But it was these two, fra. Knežević and his mentor, fra. Jukič, who left deepest mark on Bosnian culture and history, while championing the notion that Catholics, Orthodox and Muslims are one nation, and Bosnia and Herzegovina country with deep cultural and historical roots. Like Jukić before him, Knežević too articulately expressed his feeling of national belonging, which he always and primarily defined as Bošnjak (Bosniak) in such a way so that include all three religious groups inhabiting Bosnia and Herzegovina. The only other cultural identity he recognized was Illyrian, as a cultural supra-identity of all South Slavs, hence his interest and activity as a member of the Illyrian movement.