You are. You have described it as "anti-Christian propaganda". Can you give some arguments for that? You can't.
The clips I've seen along with movie descriptions make apparent the obvious falsehoods contained in the movie that earn it the title "propaganda". The righteous Muslim Turk victorious over his hedonistic Christian enemies, making direct references to Qur'anic prophecy. Now, is it in this respect any worse than most American war films? I don't know. Probably not. As you say, I'd have to see the whole thing to review it. However, the Ottoman victory over the Byzantines is not just an event that occurred long in the past. The film aims to stir up the same Turkish imperialist sentiments that are the reason half of the Orthodox island of Cyprus is till under occupation - you can go and see for yourself how every Turkish mosque in the southern part of the island has been kept pristine while every church and monastery in the north have become mosques, post offices, cafes, barns, or simply left to decay - or why using the phrase "Armenian genocide" can lead to imprisonment.
I would quite like to see the full movie, so if anyone finds a version with subtitles I'd be grateful. When I've watched the whole thing, I'll be in a position to give a 'review'. That it is propaganda, however, and of a kind that is an affront to Orthodox Christians, can easily be discerned without a full viewing.
Should it be banned? Of course not. Again, I am not applauding Lebanon for banning movies. No movie should be banned, unless it's snuff, or child porn or something like that. What I do think is positive is that they are making an effort to treat religious minorities with equal dignity. I don't agree with the rule. But if you have a rule, at least apply it equally to everyone. That's my point.