I think this is related to saying "I hate you" to a parent you're angry at when you're little. She's saying something very inappropriate out of anger - not good, but not really surprising. Because she is so little, she doesn't fully appreciate the gravity of what she is saying, she's just angry and expressing her anger.
My two cents (take it or leave it according to its usefulness to you): I tend to think that the moment of correction, when a child might be feeling guilty & angry is not the best time to mention God or the Bible. I try to instead wait until the anger of the moment has passed and the child is feeling calm & loving again - maybe at bed time when reviewing the days events, or telling a bed time story. then they tend to be much more receptive to moral lessons, words of instruction from God & parents.
I really like Jacob Abbott's examples of how to deal with these types of issues in this book:
http://www.gutenberg.org/ebooks/11667