the problem in lebanon, as i understand it, is fear. the christians in lebanon are deeply fearful of the muslims, and essentially willing to do what they're told to avoid sharia law. this is a horrific situation and not something that should be tolerated by the west, but trying to get the christians to choose to fight over submission is a historical problem that goes back centuries. unlike muslims and jews, christians legitimately don't like to fight.
however, there is a natural alliance between the maronites and the israelis and it could lead to a lasting peace if you could convince the lebanese of it's utility. as the issue is fear, the israelis should propose to protect the maronites (and the druze and sunnis) from the shi'ite muslims, in exchange for collaboration.
if israel can present the idea effectively, this is an opportunity to win their freedom that the christians in lebanon might not see again for a long time. they should choose to align on the right side of history and rise up and take control of their own destiny, with help from israel and, hopefully, a nato willing to pull it's head out of it's ass and make a correct choice for once.
the other option is going to be catastrophic for everybody in the region, and there's no other clear way to avoid it.