Heresy in the Roman Empire.

The split of the western portion of the empire from Constantine's Eastern portion:

 With the adoption of Christianity Constantine paved the way for the later Roman Empire fully adopting Christianity. At this point- Christians are no longer persecuted as they were during the previous Western Empire.
 A dangerous shift for humanity happened at this point; heresy no longer meant a cold shoulder to those who did not conform, but rather, heresy now became a crime punishable by law; those who institute and enforce laws working against individual thought are committing an atrocity against human rights. The root of all progress and great accomplishments have come from those individuals who are willing to be different, have original thought and ultimately become outcasts of society: Socrates, Einstein and  Newton to name a few.
In the end, the criminalization of heresy is just one expression of the intolerance which has come to be exemplified in our history.