A friend recently made a short comment, “Antinomianism is the fashionable heresy today.” I hadn’t seen it before, but he’s right. Antinomianism has been around since the early church battled with the gnostics, but it gained its name in the wake of the rise of Lutheranism.
Antinomianism is the heresy that once you are saved you don’t have to bother with the moral laws. You can see how it flourished: If, as the Protestants taught, you were saved by faith through grace alone and not through good works, then one might conclude that good works and morality generally don’t matter.
Under the Manicheans and other gnostic sects (and later the Albigensians) the emphasis was not so much on salvation by faith as it was on a belief that the “spiritual” was superior to the physical realm and consequently the sins of the flesh were no big deal. Sometimes this was also expressed through extreme asceticism: if the physical was inferior then it was bad and it needed to be suppressed so the “spiritual” could flourish.