I’d love to see a (civil, philosophical) discussion on the question above. Though I ask for a view on whether or not Christians should do this, I would also be interested in hearing from Jews and Muslims about whether it is advisable (or not) for believers in their respective traditions to take up the Asian martial arts — and if so, under what conditions might that be OK?
The problem, it seems to me, as someone who has never practiced a martial art, comes from the fact that many (most? all?) of the martial arts are grounded in a certain spiritual and metaphysical worldview incompatible with Abrahamic religion. To what extent is this an issue, do you believe? Is it possible to practice martial arts without opening up oneself to the spiritual aspects, and/or consciously rejecting the metaphysical parts? Or is it an all-or-nothing proposition? How does one discern what is good in these disciplines (from an Abrahamic point of view), and what is to be rejected?