Martial arts have sometimes been compared to religions in their spiritual approach. This is a misconception. Karate merely gives the practitioner the tools to use his mind and body effectively and wisely.
Self-improvement is the guiding light of the karate-ka. The only religions that find the principles of karate inconsistent with their beliefs are those that disapprove of self improvement; and the writers are not aware of any mainstream religion that adopts such a philosophy.