User blog comment:B214/Question and Answers 6/@comment-185.112.105.215-20161019113453/@comment-29963364-20161020005824

You seem to forget that the Biblical God wasn't the only god to create a "system." There are other faiths with there own "systems", so it makes sense that their sutras, and other rituals & items of similar nature, would be extra effective (even deadly) to "evil forces."

And I never said "Holy Power" was needed to make holy water, crosses, etc. deadly to Devils, the "Heaven System" just makes them that way.

Example: In vol. 4, Issei requested that Michael tweek the "Heaven System" so Asia and Xenovia can freely pray without the nasty headache. The Devils aren't bombarded with "Holy Power" when they pray, the "system" just takes effect. Same when they touch crosses and holy water.