Allah sealed hearts of these non-muslims who whine against so called attrocities by Muslims historically. So they listen not any argument. See not any abberation in their fallacious thinking.
But this seal by Allah non their heart is aimed at punishing we muslims. we too have gone too much down by standards of Islam.
So Allah, I am afraid awnts to punish us first by these people; and then reove seal from their heart, lest they can see Truth of Islam.