There is more to it, than what the others have said...and I am going to actually answer your question based on my own knowledge on Judaism.

In Judaism, there is no other higher being than God himself. Only God is worshipped and no one else, and this is one of the 10 commandments headed by God to Moses to lead the Jewish people. Also, in Judaism, they believe that their people are the favourites, the chosen ones picked by God to live by his way through the Torah, through the commandments - therefore, they would see both Christianity and Islam as discourses of their own religion.

Islam on the other hand, recognises both Judaism and Christianity. However, believe that their religion is the final product of lessons taught after the "failings" (quite possibly with Jesus) of Judaism and Christianity.