left/right completely falls apart when you apply it to groups like ISIS. They're decidedly not capitalist, which is strongly associated with "right wing", they run/ran their system on a religious taxation-scheme with a lot of "nationalization" of anything in conquered areas, but they're also not marxist in any way. They are obviously not nationalistic and are a diverse group, they are united by belief/ideology, not by blood/heritage.
Declaring them to be "right wing" is obviously nonsense unless you remove all meaning and just call "right wing" whatever isn't explicitly left wing.