[atheistwithfaith]

It seems that nobody really knows about the JET selection system at all. Some people claim that being able to speak Japanese or having teaching experience hurts your chances. Through all my reading I would personally say it has very little bearing on the decision, if not actually helping your chances. It seems the selectors place a lot of emphasis on how well your interview goes. Though by the time you do it, this may have changed and having that degree may be of great benefit - its impossible to say.

That said, your employer / colleagues in Japan will greatly appreciate someone with teaching experience and Japanese language ability. You yourself will also find the experience more enjoyable from the get go and will probably get a lot more out of it if you have those assets.

Short answer: No it should not hurt your chances.