the labeling that I’m using here is justified because it informs us about the motivations of the people carrying out these actions, and motivations are important. certain attributes may be entirely contingent, sex, hair colour, skin colour, what they had for breakfast that day, etc. - they have no bearing on the reasons those actions were carried out. other attributes are important in a causal sense though; and when it comes to terrorism, ideological attributes are chief among these causal attributes. as I explained before, for an IRA terrorist religious doctrine was not a causal attribute, that was stuff like anti-colonialism, Marxism, etc., but for an Islamist terrorist religious doctrine is extremely important (along with anti-colonialism and other political factors - I’m not claiming it’s the sole justification), failure to recognise this is just willful ignorance at this point.
the semantic point you’re making is invalid as well. a religion cannot do anything, and there is no “leader” of Islam. it is only that people base their actions on religious teachings that is important, and however rightly or wrongly they interpret their religions according to others is irrelevant, it is enough that a reasonable link can be established between a set of teachings/principles/texts/etc. if somebody draws an inference about all Muslims from my categorisation of an individual terrorist who happens to be a Muslim then they’re a bigot, and an illogical one at that, but that’s their problem.
tl;dr: I am talking about terrorism in support of ideology X, not terrorism by person with contingent property X. such a sentence makes no logical claims about all people who follow X, or all possible interpretations of X - that’s just projection on your part.