To be honest, no one knows what true Islam is anyway.
When it comes to jurisprudence, there are four main schools of thought (there used to be more):
Hanafi (the oldest of the four, generally tolerates the other three)
Maliki (has not tolerated the Hanafi historically, but does today)
Shafi (has not tolerated the Hanafi historically, but does today)
Hanbali (has not tolerated the Hanafi historically, and still does not to this day)
When it comes to theology, there are three main schools thought:
Athari (used to be considered orthodox, and condemns all other schools)
Ashari (considered orthodox since perhaps Imam Ghazzali)
Maturidi (considered orthodox since sometime in the Medieval period)
Muslim scholars also believe in the concept of infallibility, which comes from ijma (consensus), but the extent of this consensus differs among them (I am not entirely sure how many of the following are still believed in):
Consensus of the Sahaba (those Muslims who witnessed Muhammad)
Consensus of the Salaf (the first three generations of Muslims)
Consensus of the Ulama (the learned ones)
Consensus of the Ummah (every Muslim from scholar to layperson)
Of course, you have the movements today like the Barelvis, Deobandis and Ahle Hadith (Salafi/Wahhabi), who systemise selections from the above, and two of the movements incorporate certain Sufi spiritualities.
And this is just Sunni Islam.
