Not true. Technically speaking, not to argue, but the last messenger idea would be a tenet of Islam, not its sole premise. Islam is, (I'm in agreement with Ernest Becker here) like the rest of religions, an "immortality project" as he described. Taking both of those into account, the arrival of another prophet would probably not bring the religion down. After all, "if Allah did not exist it would necessary to invent Him." ; )
Funny thing happened on the way to Islam. Read here about the origins of Islam and how no one can find any early texts. http://www.bible.ca/islam/islam-myths-koran-manuscripts.htm
The truth of any ancient text, is that we don't know. Look, we have a Constitution in this country that we claim to have the original of...less than 300 years old...and do we see complete agreement on what every word means, in context, etc.? Nope. So if we see as much conflict in America about what the Constitution actually means and how it should be enforced...then what to expect from any religion, where the followers believe the text is Divinely inspired? If, and only if, each and every Muslim interpreted what they read in exactly the same way as the extremists do, would we be in real trouble. Since they don't, the problem really only exists among the extremist factions...which has always been the problem with extremist of any religion, ideology, faction, etc. I get such a kick out of watching the Christians saying that moderate Muslims are not following Islam properly...as if they know?
Nearly every religion has two aspects to it. 1. The creed and dogma that have to do with the world and how to live in it. It is external. 2. The spiritual aspect of the religion that has nothing to do with creed and dogma and the world, but the relationship between the soul and God. At present, a review of most of the world's religions, especially those born in the middle east, i.e. Islam, Christianity, and Judaism focus mostly on the 1st aspect...the external world, and not the inner world of soul and God.
Let's review... first you wrote "the crusade was" and only after I corrected you did you acknowledge there was more than one. Then you edited your mistake out of a reply, then you said it was context, then you said it was a typo, and now you're trying to obfuscate. When your mommy changes your diaper and spanks you for being a lying troll, ask her to show you how to use google.
So your still skirting round the subject of the 20 Crusades come on man up and admit you were wrong. Whats this in your posts about diapers and spanking are you into scat and adult baby stuff