I've been having a fantastic debate with Evangelical Christians over the past little while and I would love to continue it. Just to briefly state what the Jewish view of Christianity's purpose is, here are the words of the Rambam (Mainmonides) in his Laws of Kings, Chapter 11:4 :
"Even Jesus the Notzri, who thought he was the Messiah... was the subject of a prophesy in the Book of Daniel (11, 14): "...also the renegades of your people will exalt themselves to fulfill the vision - but they will stumble." Could there be a greater stumbling block than this [Jesus]? For all the prophets spoke of the Messiah who will redeem and save Israel, who will ingather all its exiles, and who will strengthen them in the fulfillment of the Torah's commandments - while he [Jesus] caused Israel to be killed by the sword, their remnants to be dispersed and humiliated, the Torah to be switched for something else, and most of the world to worship a G-d other than the G-d of Israel! But - the thoughts of G-d cannot be fathomed by human minds. For our ways are not like His, and our thoughts are not like His. All these activities of Jesus the Notzri, and the Ishmaelite [Muhammad] who came after him, are all for the purpose of paving the way for the true King Messiah, and preparing the entire world to worship G-d together, as is written (Tzefaniah 3,9): 'For then I will convert the nations to a pure language, that they may all call in the name of G-d and serve Him together.'
"How will this work? For by then, the world will already be filled with the idea of Messiah, and Torah, and commandments, even in far-off islands and in closed-hearted nations, where they engage in discussions on the Torah's commandments: some say that the Torah's commandments are true but are no longer binding in these times, while others say that there are hidden, deep meanings to them, and that the Messiah has come and revealed their hidden secrets. But when the true King Messiah arrives, and will succeed and will raise them up, all the peoples will immediately realize that they had been taught lies by their forefathers, and that their ancestors and prophets had misled them."
Christianity and Islam serve to bring Biblical stories, concepts and ideas to a largely pagan world. Today, over half of the world's inhabitants follow an Abrahamic religion. These two religions are tools through which G-d will bring the true messiah.
The Torah is not just for Jews but for non-Jews as well. Jews were given 613 commandments and non-Jews 7 commandments to follow. They are:
1) DO NOT COMMIT BLASPHEMY
2) DO NOT WORSHIP IDOLS
3) DO NOT COMMIT THEFT
4) DO NOT COMMIT MURDER
5) DO NOT COMMIT SEXUAL IMMORALITY
6) ESTABLISH COURTS OF JUSTICE
7) DO NOT EAT THE FLESH OF A LIVING ANIMAL
To learn more about these laws, visit Noahide Nations, Christianity Revealed or Ask Noah.