What does " intra-Abrahamic fault lines" mean?

English is not my mother tongue and I’m a atheist. Now I’m reading “Decoding God’s Changling Moods” in time.com, the full article you can find here:

http://www.time.com/time/magazine/article/0,9171,1902851,00.html

and i can’t understand the last sentence in 7th paragraph, “the most dangerous of intra-Abrahamic fault lines, the one between Muslims and Jews”
What does that mean, who can explain it? Thank you.