Note: these are not the ONLY reasons nor are they necessarily the BEST reasons - I am assuming this list will be updated from time to time.
But for this morning, here's my list:
waterboarding is torture and that torture is a war crime.
The GOP candidate for the Oval Office has advocated committing war crimes.
Let that sink in for a second.
That alone disqualifies him for the highest office in the land and should have disqualified him from the start.