"But since our discourse has now turned to the subject of blasphemy, I desire to ask one favor of you all, in return for this my address, and speaking with you; which is, that you will correct on my behalf the blasphemers of this city. And should you hear any one in the public thoroughfare, or in the midst of the forum, blaspheming God; go up to him and rebuke him; and should it be necessary to inflict blows, spare not to do so. Smite him on the face; strike his mouth; sanctify your hand with the blow, and if any should accuse you, and drag you to the place of justice, follow them thither; and when the judge on the bench calls you to account, say boldly that the man blasphemed the King of angels! For if it be necessary to punish those who blaspheme an earthly king, much more so those who insult God."
--St. John Chrysostom
Not saying he condones vigilantiism or condemnation, but allowing blasphemy in the name of liberty perverts liberty and endangers the whole city and society.