Re: Aikido and being Christian
As Jonathan has said, there ARE fundamental differences between Christianity and Zen Buddhism.
1. Zen Buddhists believe that one can achieve ‘enlightenment' (or heaven on earth) by self-mastery. Christians believe that one can only gain entrance to Heaven through Christ.
2. Zen Buddhism teaches meditation as a process of purging unwanted thoughts, emotions, habits, etc. (which can be construed as an ‘emptying of the mind'), whereas Christian ‘meditation' is actually ‘contemplation'.
3. Zen Buddhists strive to purge themselves of desire to regain purity (and thus transcend ‘hell on earth'), whereas all of the Christian teachings reinforce that righteous desire through Christ is what makes life on earth worth living.
If I remember correctly (what limited knowledge I was told from various sensei) Omoto-Kyo differs fundamentally in that Omoto-Kyo followers believe that various people are/were reincarnations of actual Gods, whereas Christians believe there is only one God, and that Jesus was God's physical manifestation on earth.
Those reasons alone are pretty powerful arguments that Christianity and ANY other religion are not ‘compatible' in the sense of muddling the two belief systems together to form some ‘personal' belief systems that subscribes to the principles of ‘both'. However, one should not discount any lesson here on earth, since truth and wisdom is found in many of God's creations (not just in the Bible). I, for one, frequently enjoy studying Zen Koans.
All that being said, IMO righteous desire in your heart, AND your Aikido is what brings the two together in harmony.