This passage is meant to ridicule a particular unnamed sect. I am not confident that It is addressing the gnostics, though some scholars belive it could be. The passage is simply to ambiguous.
There is much to be said for the fact that the gnostics may have been the original Christians. The gnostic sects were mystery religions, just as modern orthodoxy is today. There were Jewish gnostic sects before Christianiy was ever though of. Most of thwritings have been destroyed and they were so insignificant they were not often written about. The parables are an excellent example of gnostic thinking, they are very clearly speaking of hidden knowlage.I hope I have given a desent answer.