Given that ISIS and the rebels are virtually indistinguishable from each other, and that both are trying to overthrow the Syrian govt, and that both are a threat to Christians (while Assad protects Christians), you are full of bull feces claiming the opposite to be true.
Oh, Lord. No way have you even been following the maps, every few weeks, showing who controls what areas, who’s attacking who, etc. For the most part, Assad’s forces have not even been in position to deal with ISIS, and they’ve been much too busy with other rebel groups to do so. ISIS has been on the defense from the US / Kurd alliance, and too busy to worry about Assad, very much. Ergo, a sort of defacto “truce” has gone on in that regard for quite a while.
ISIS and the AQ leaning rebels are similarly “bad” in a number of ways, but to say they are “indistinguishable” is just ignorant. (I’m not responsible if you continue to demonstrate such.) Now, within the AQ leaning group of groups, THAT’s where things get very blurry, alliances constantly shift, etc.
Last, the Kurds with US backing have been the major factor in taking down ISIS. Period.