Hillary Clinton Should RESIGN Over Ambassador's Death ... Says Ben Stein

Hillary Clinton should take FULL BLAME for the murder of J. Christopher Stevens -- the slain U.S. Ambassador to Libya -- and should resign from her position as U.S. Secretary of State ASAP ... this according to Ben Stein.

Stein -- who went to law school with Clinton at Yale and was a member of President Nixon's staff -- was at LAX yesterday ... when he told us, "It was her fault ... and he didn't have adequate security."

52-year-old Stevens died on Sept. 11 during an attack on a U.S. compound in Libya. Clinton now says the U.S. believes the attack was perpetrated by Al Qaeda.