Actually, as I suggested earlier on this topic, the whole idea of belief as necessary to salvation is pretty exclusively a Biblical concept. I don't know that Mohammed even made any statements that are a matter of belief. The Koran is mostly a set of instructions to obey, not propositions to believe -- "believe in the Last Day" is the only exhortation to belief that I can think of, and it's not an exhortation to take somebody at his word, just a general exhortation to believe in a concept.
If you don't belive in Allah there's a pretty nasty hell waiting for you where your skin gets replaced to burn again, And Allah knows best.
"There is no God but Allah and Muhammud is his Phophet" are two very specific belief claims made by the Qu'ran. Muslims go you Christians one better as they make these beliefs publicly five times a day.