A Refutation of the Quran's Understanding of Judaism By Josef Gabai

The transmission of the Laws of the Torah and its teachings has been faithfully practiced from Moses at Sinai until this day. Jews can never accept the claim by any leader of any people that he was sent to replace Judaism. It is simply a false claim.

Likewise, because of their status as God's elected people, Israel never gets away with their transgressions. When the Divine Justice strikes them, it is not because they are rejected by God, as the Quran claims (Surah 5:18), rather, it is on account of their proximity to God.

Maimonides writes: 

Just as God is everlasting, so is His Torah. No one may add to it nor remove any law from it, as it says: "The entire word that I command you, that shall you observe to do, you shall not add to it and you shall not subtract from it" (Deuteronomy 13:1). Therefore, if a man, be he Jew or gentile, will declare that God sent him to add a commandment to the Torah of Moses or subtract from it, or to add an explanation which we have not learned from Moses or who would claim that those commandments which the Israelites have inherited are not for all generations to come, this man is a false prophet.

.(Maimonides, Laws of Torah Principles, 9:1)