JGN, no it is not taken from other scriptures. We as Muslims believe in prophets Moses(pbuh), Jesus(pbuh) and all others mentioned in Quran.
Islam is not new, it from the days of Adam(pbuh). Prophets have been sent time to time. Muhammed (pbuh) was the last prophet and Quran was the Book. The current version bible is not he same given to Jesus(pbuh) and Torah is not the same given to Moses(pbuh). You visit any bookshop you find 100 different version these.
However look for Quran, it is the same as was revealed 1400 years ago. It is the promise of Allah the Quran will remain intact and it is. It is a challenge of Allah to mankind to produce another book like Quran or a chapter, 1400 years have passed by and mankind is unable to produce a single chapter.
