by Sally Matheny     There’s a children’s picture book, Sister Apple, Sister Pig, causing a great disturbance among conservative Christians. The theme of the book is abortion. Thankfully, this book is only available online and isn’t readily available in your child’s library. I read the free e-book. Then I read the reviews and interviews. I can see why the response was so intense.   What Makes People Angry   The author, Mary Walling Blackburn, presents the topic of abortion in the form of a children’s picture book. While she says it is meant for adults, not children, it is still formatted as a children’s book and the main character…