The DNC put a Muslim family on stage at their convention to personally attack Trump; specifically his patriotism. The attack was launched under the guise of honoring a fallen soldier and making unrelated comparisons between the soldier and Trump.
First off, comparing this soldier to any of the politicians running in this election would have produced the same results; there's no comparison. Secondly, to use a fallen military hero and their family as political fodder is both inexcusable and immoral.
This tactic, much like associating Trump with alleged Russian espionage shows how desparate the political Establishment (both sides) is to take down the sole remaining anti-establishment "outsider."
Donald Trump’s Confrontation With Muslim Soldier’s Parents Emerges as Unexpected Flash Point - The New York Times