I just read a recent article by T.K. Chiba, Sensei about Aikido and Zen at http://www.aikidoonline.com
It was a really interesting article about his spiritual approach to aikido. He diverged from O'Sensei in following Shinto basically because he did identify with the Shintoism. The article does a better job than I could explain.
Anne Marie Giri
5th kyu, Florida Aikikai