On Quietism
John Michael Talbot

Quietism is a later western heresy. In its less harmful expression it is exemlified by Abbot Fenelon, and Madam Guyon. In its most harmful expression it is exemplified by Molinos. It started out as legitimate contemplation, whereby teaching on morality and doctrine serve as steps towards mystical union, but lapsed into the teaching that as long as one is in contemplation, morality and doctrine are no longer relevant.

The dangers are obvious. Lapses into immorality follow pretty quickly when this teaching is fully embraced. Interestingly, many non Christian contemplative traditions, such as Zen, have also delt with this phenomenon, and  have condemned it.

So true contemplation sees the objective teaching of the Church on faith and morality as positive steps and discernment tools in moving towards legitimate contemplation, which is beyond any description or objective knowledge. But once the contemplative stage is reached, one continues to fulfill, and be properly concerned with, the objective teachings on faith and morality.

If anything, one can now fulfill them more effectively because of the grace of contemplation, except during temptations and dark nights, which can sometimes become more intense once the higher levels of prayer are reached.

I hope this is somewhat helpful. You may want to read in Tanquerey's, "The Spiritual Life," or some of Jordan Aumann's works for further study. 
John Michael Talbot