There are no conflicts among true Muslims throughout the world. There is only fighting between true Muslims and false Muslim pretenders. Whichever side is victorious are the true Muslims because Allah gave them the victory.
Not sure why the actual fallacy type relevant to this is not included, but what you said is basically "No True Scotsman" fallacy.
P1: All X are Y.
P2: Clearly, not all X are Y.
C1: All true X are Y.
In your eyes they are not true muslims, in their eyes they are muslims,
since they don't abide by the original claim, you assume they are not "true"
Furthermore, the assumption that one of the sides will win because allah gave them the victory is also a fallacy.