What was the justification of morality in Puritan Antinomianism?

As far as I know, Puritans were devout Calvinists. According to Theopedia, [Antinomianism](http://www.theopedia.com/Antinomianism) is associated with disobedience to the established authority, so it may be connected with the idea of lawlessness, immorality, or licentiousness. Was this term merely a pejorative adjective for people who disagreed with the established religious authority, like legalism? Or did the Puritan antinomians really have their own theology on justification before God, and if so, how did the Puritan antinomians thought they were justified? What was the purpose of God's moral laws then? This question was previously posted on the History.SE , but it was closed for being off-topic. Hopefully, it's on-topic here.