We know from recent history that mass murders are not limited to ISIS. Columbine was not ISIS. We have had several such cases. The guy's father was on the FBI's most wanted list. Bad DNA can produce a sick SOB.
I think more anti-Trump than ISIS inspired.
Most mass murderers are liberal. That is because liberals already have diseased minds, so they are more likely to go over the edge, so to speak. Add to that the surge in conversions to Islam by liberals (following the lead of the life-long muzzy who usurped the White House for 8 years, and well-known converts like Al Gore, the Clintons, and Al Franken), and it’s a toxic mix.