I will respectfully disagree.  I don't see any HS team beating a D3 college team.  Maybe - and I say maybe - if you took a state championship team from TX, FL, GA or CA, they might be able to give a D3 team a game.  but you're still talking about 17-year old kids facing players who are older, more mature, and have benefitted from several years in a college strength and conditioning program. 
now, this year's version is not one of St. John's better teams, but they still have a QB who is among the top D3 passers in the country.  their defense is the issue.