It seems you hate being wrong, but you'd look better if you simply admitted it.
How do I know so much about Islam?
I was one of them for 21 years of my life.
Islam is not a religion like Christianity which can be changed.
The Qu'ran is considered the word of god and Allah has already said that it will never change.
Therefore if Islam changes then it will no longer be Islam.
In fact, the Shia changed their version to Shia'ism, the Sufis to Sufism, etc.
The form of Islam which is closest to that practiced by Muhammad is Wahabism and is the driving force behind Islamic terrorism today.
By the way, the closest to real Christians would appear to be the Jehovah's Witnesses. Although I could be wrong on that, as my knowledge of Christianity is fairly poor.
But my knowledge of Islam is second to none. It's a fascinating religion, albeit one of man's greatest mistakes.