The Truth Replaced

What have they done? The Truth they replaced by majority rule. The Halacha was to be determined by the Rov, the majority. That is what the Chachamim have done, the Anshei Knesset HaGedolah. Together we will decide, they said, we, not G-d, together. About this, David HaMelech said (Tehilim 14, see also Tehilim 53):

יהוה-- משמיים, השקיף על-בני-אדם
לראות, היש משכיל-- דורש, את-אלוהים
הכול סר, יחדיו נאלחו: אין עושה-טוב--אין, גם-אחד

HaShem-- From Heaven He gazed down to man to see if there be one that reflects, one who seeks G-d. They have all gone astray, together gotten polluted, none does good, not even one.

Did they do wrong? They caused enormous pain, על ה' ועל משיחו.