The idiot liberal media will, of course, completely misunderstand what Phil Robertson is saying and label him a “Christian Taliban” or some such nonsense.
The members of ISIS are engaging in acts of depraved evil: murdering children by dismemberment, persecution of Christians and Jews, and seek to create mayhem and war wherever they can.
This kind of serious, depraved evil only has two solutions: one is for God to reveal Himself to them, for them to put their own pride and selves aside, and to embrace the gospel of Jesus Christ, because that Word is the only thing that can cleanse them of their sins.
But God does not force anyone to accept Him. If they reject Him (as seems likely) then the kind of evil they perpetuate can only be dealt with in one way.
Clarifying my point a bit: the short version, they either convert to a different way of thinking that doesn’t involving killing all non-muslims, or we have no choice but to defend ourselves, which means destroying them root and branch.