That sounds like a pretty bizarre idea. The bit about it being devil's own language I can understand coming from someone who is finding it very difficult to master Japanese. Maybe this was something said by someone like Francis Xavier or some other missionary in Japan?
 
Do you have the original Japanese?

Quote from Yuki on 07/21/10 at 13:09:26:

Just as much as your own language is associated with demonic activities.   Or mine is.   Because obviously the only true christian language is hebrew.   Well, until the true language became greek.   But as well know, the latin that followed must be the be it all end it all of the one true god which at 11 different religions claim is their´s alone.
 
Of course i could take the side that christianity is demonic influence and that then, by logic, Japanese becomes the divine language thwarting the spread of such an evil cult.
 
 
I think the origin of the quote is some religious fanatic in the 16-17th century, one of the early "missionaries" who got upset because they couldnt do Japan conquistador style.   But i could recall incorrectly.

Yuki, I'm not sure if you are the same poster but you already brought this up at two other forum groups.
 
http://www.japanforum.com/forum/japanese-language-help/32924-weird-thing-deserve s-its-own-thread.html
 
http://www.jlptstudy.com/forum/viewtopic.php?p=921&sid=f3c3cdb93afe437feccc5 4dce87e7f11
 
The source of that quote seems to point mainly to an article on Japanese Language written by a Tae Kim.  Whether it's an original quote he came up with on his own or lifted it off some archaic scribe somewhere else I don't know.  I also don't know what his intentions were, whether he meant it to be inflammatory, a joke or some sort of political jab.  Maybe his site got hacked and someone added that in?
 
The quote is meant to spark a "flame war" and should be ignored as such.
 
http://www.guidetojapanese.org/wiki/index.php/The_Writing_System