Sacrifices are an often reoccurring theme in the Torah. The Quran too acknowledges that animal sacrifice was commanded by God in the time of Moses (Surah 2, Al Baqarah, verse 67). Its main meaning was that it made atonement, it took away the sins of the people who offered it (Leviticus 17:11).
This novel was written for Muslims. In particular, it was written for Muslims who are curious about Christianity but do not know how to satisfy their curiosity. You may be afraid of asking certain questions because you fear the reprisal of your peers.