Ok to explain the concept - christains believe that anything not from God is from Satan, and that because they have the holy spirit (God's spirit) living inside of them they should not expose themselves to unholy things because it is dishonourable, disrespectful and hurtful to the spirit of God and themselves.
However, put simply as a Christian I find this is an extremist view on the passage in the Bible (ill find it later if you like) and it is taking what has been said out of context. If you really want to prove this point ask her whether or not she uses a car/watches television or does any number of things that God has not directly created.
If i do a drawing of an angel like being but it isn't intentionall representing an angel from God is it therefore demonic? see the paradox? tell her to pray and read the passage again, as christian we can be like sponges taking on other christians crazy extreme views far far too easily.
I once knew one who wouldn't eat chocolate because it releases endorphins the same hormones released during sex, points for guessing why ouldn't eat it. (that case ended in me asking if she ever did any exercise... anywho moan over) Good Luck
