Some people profess to be puzzled by Barack Obama's reluctance to use the terms "Islamic terrorism," "radical Islamic terrorism," and "Islamism." I think it's pretty simple. Obama sincerely believes that Islam is a great and peaceful religion. This doesn't mean that every adherent of Islam is peaceful. It means that the religion itself, viewed as a religion, is peaceful. Obama is afraid that if he links terrorism to Islam, uneducated people will think it's the religion itself rather than a small subset of its fanatical adherents that's at fault. Why risk this? Why take a chance that even one person will think Islam per se is at fault for the terrorist attacks being made around the world?
It's really that simple. But notice the implication. Not everyone is as smart as Obama. He knows that the religion is peaceful, but many Americans do not. By speaking carefully (some would say "dishonestly"), he avoids linking the religion (Islam) to the terrorism in people's minds. So it comes down to condescension. Obama alters the way he speaks in order to keep the yahoos from drawing an erroneous conclusion.
A respectful leader would speak openly and clearly to the people, and not assume that they are too stupid to keep the religion and its fanatics separate. Leftists are fond of playing around with language to achieve their ends. This is but one example of it. It's called "manipulative rhetoric," or rhetoric in the service of a cause. George Lakoff has been at the forefront of efforts to help leftists frame issues by using carefully chosen emotive language.
Donald Trump appeals to many of us because he doesn't play these linguistic games. He trusts people to know the difference between Islam (the religion) and Muslims who act in the name of their religion. An honest discussion of the problem of terrorism would include reading those parts of the Koran that deal with how Muslims should treat nonMuslims. Is terrorism indigenous to Islam, in other words, or foreign to it? Almost nobody in the mainstream media wants to touch this issue, so all we get are platitudes from the likes of Obama to the effect that Islam is peaceful and would never sanction or support terrorism.