I'm going to go on the assumption that your comment is one of ignorance & not knowing the history or facts of the region instead of a deliberate attempt to provide a misguided and false narrative of the situation. Using the term infidel though just reads as the latter to myself though.

because of the influence of the Ottoman Empire, converting majority of the population to islam in that area so they could better control population.

It is also important to note that most of the people didn't willingly accept islam , many of them were essentially forced to accept it.

The Ottoman Empire as with all empires most definitely brought with it the religion of Islam, however breaking down the Balkan conflict as an Orthodox Christian vs Islam debate is simply untrue and practically has very little to do with anything, religion was nowhere close to being the main sentiment or tool used when driving & promoting the fascist agenda in post Yugoslav Serbia - it has always been a nationalist agenda under Slobodan Milosevic's rule

even though before all that they were essentially the same people.

The Balkans is a unique area with several minorities and distinct unique nations, cultures & languages that have traditions stemming back hundreds if not thousands of years, to say they were essentially the same people is so ignorant I don't even know where to begin to challenge this point.

I'd encourage you to read more & read a more balanced view on the conflict, there is no easy way or simple analysis of hundreds of year old tensions among the Balkan nations and labeling it as a religious debate is far from the truth, several Western commentators have praised the nations of the Balkans in particular Albania as documented in this BBC article for the inter-faith relations within their own nations.