Don't the Jesuits do spritual exercises that are reminiscent of gnosticism anyway. They just wanted to be the only ones to have the Gnosis, which is fair enough but not very ethical.
The debate over the authorship surely comes down to whether the disciples were affiliated with the community. It seems more than likely to me as they held off the Romans for nearly two hundred years didn't they? More seems to fit with what we know than not i.e. he was a devout jew, a reformer, he opposed the romans. Just because it doesn't fit with what christianity became doesn't mean they didn't have the same source.