Coelacanth, Who said they all were not muslim? The one who Believes and prays to One Almighty, the Only Creator, and accepts his Prophets and Messengers (not considers)and follows their teachings is a Muslim. Islam is the religion taught by Almighty to the Mankind through several revelations which uprgaded time to time by HIM. The other religions are made by the followers of Those Prophets by altering their teaching after their period. Adam (AS) was Muslim, Moosa(AS) was Muslim, Isa (AS) is muslim. Muslim accept all those Prophets as Prophet of Almighty and we accept their teachings. It is sure that Islam is the only salvation. If dmightysolomon or anyone else Believe on The Almighty, Only creator and accepts the teachings of The last prophet will get salvation.
There is nothing to confuse. It is very clear, Almighty has sent Many Prophets/Messengers in times and He sent the Last Prophet with His Final revelation for the rest of Mankind. There Islam completes. These teachings to be followed by one who will be alive until the end of universe to get salvation. The Jews and Christians were doing the right things when their Prophets were present and later they altered the teachings according to the peoples comfort. Like christians are eating pork which is forbidden for them. Jews started worshipping cows etc.