How well did it work for Jugoslavia, Lebanon, Azerbaijan and Syria?
It is not a "best bet". It is a long shot and it misses most of the time. The best bet is to stay homogenous.
"otherizing Christians living across the border" might sound bad, but it won't lead to genocide because they have their own country with their military and police and you can't just walk in and kill them (they can neither).
You can have wars but those rarely result in genocide. Civil wars had much worse outlook on that.
However when there are Christians (or Muslim) in your country, it's pretty real that suddently the regime wants to kill them with their military and police and they have no force to stand up for them.