Let me just say, I am a Christian myself and some of my least favorite people are other Christians. I am really unsettled by people who interpret things literally. Snakes are called evil because Satan took the form of one in Eden, yet whales are not called evil because one swallowed Jonah, nor are calves called evil because Aaron made an idol out of one.... the logic is ridiculous. What about all of the evil things PEOPLE have done, before, during, and after the bible. Anyway, enough of that rant.....

I have found that when you engage these people in a religious debate, you can back them into a corner so fast they usually end up stuttering in tears. Not that you have to be nasty, you can question them as nicely and reasonably as possible and they will still be speechless.

"Why do you think I am a Satan worshiper because I have snakes?"
"Satan tempted Eve in the form of a serpent."
"How are all snakes bad because of the actions and use of one?"
"No other animal has been called Satan."
"Can you say that all human are bad because some worship Satan? Are we all murderers because some people murder?....."

You will never get a civil response like, "oh, that is a really good point" from people like this. But you can make them go away and stop talking to you. They will always be right in their mind. I saw it all the time and stopped going to church. I now worship privately. So, your options are to engage her in a conversation to nowhere, or to ignore it. You will never convince her that she is a ridiculous person that needs to just stop saying words.