It is historically documented that Bosnian Church was the state religion before the crusaders and before the arrival of franciscans and that this religion was the religon of the bosniak people (then called bosnjanins). However some were forced to convert to catholicism and some were so brainwashed that they accepted catholicism. Thoose who bravely kept their religion to the arrival of turks directly accepted Islam while those catholics who accepted Islam were simply Bosnian bogumils who earlier had converted to catholicism. Since Bosnia was and still is kind of isolated then there were no strong religion and people could change religion every week. That is why many Bosnians accepted Islam.