How can it possibly be the fault of the religion itself? A religion has no physical being. It cannot wield a sword, pull a trigger, or manufacture an IED. People do these things, not religions. By the same token, terrorism perpetrated in the 1970s by the Red Brigade and the Baader Meinhof gang was not the fault of Marxism. In such cases terrorism done in the name of Islam/Marxism/whatever is the product of those whose warped ideology leads to the conclusion that mass slaughter and other atrocities are acceptable in the name of Jihad/International Communism/whatever. It is not the product of the ideology/theology.whatever itself.
Specifically in relation to Islam, there are something like 1.6billion practising muslims worldwide. A tiny proportion actually commit atrocities in the name of their religion. If violence against non-believers was a fundamental article of faith rather than a particular twisted view of the requirements of the faith, you would expect rather more of that 1.6billion to be party to it.
Besides, consider the alternative. Suppose President Trump declared that Islam itself represents an evil empire which threatens the very existence of western civilisation. Can you think of a better recruiting sergeant for ISIS?
Blaming the fucktards who perpetrate this sort of abuse (a significant number of whom do present with recognised mental health issues) rather than the religion in itself is nothing to do with being PC, it has got everything to do with identifying where (IMHO) the true blame lies for a 17 year old with mental health issues deciding to pick up an axe and go swinging it on a commuter train.