[Hope]

Sunni, Shia, Ahmadiya, Whabbi, Salafi, Mohammedans, Sufi...Islam also has divisions.  And they kill each other.  I will not mock like Hope who said we need Jesus to UNITE the various Christian denominations, so I will not say Muslims need Muhammad to unite their sects.

Rather, I could say that Islam is a Christian denomination that has a different doctrine, just like the Roman Catholic Church has a different doctrine from the Protestant Church, and within Protestantism, there are further differences just like within Islam, they have different sects which Christians call denominations.  Sect or denomination, they mean the same thing.

If you have a totally different theology and a book which can stand on its own, you are a different religion. 

If you start with the Old Testament, then take from the Psalms and cherry-pick from other books of the Bible to build your own, then you are just doing what Christian churches do...some accept the Apocryphal, some reject it.... or if they accept certain books in the Bible, they have different understandings and emphasis, just like the way Ali is cherry-picking verses in the bible here and there to suit his narrative, then yours is not a separate religion but a denomination of Christianity.

The Quran cannot stand on its own, it needs the OT, Psalms, and its own version of the Gospel that rejects Paul, saying that he is a false prophet, and therefore Muslims are basically Christians who follow a denomination called Islam...that's all.

Ahamadis are not Muslim.You know why? The founder of Ahamadi claimed he was the promised Messiah, Jesus.How can a Punjabi become a Jesus, who was an Israelites?
Mohamadan was a term  used to ref Islam by westerners in the past.I think it is not used anymore.
Sunni, Shia,Wahabi,Sufi,Salafi all including heretic ahamadi are using SAME and ONE Quran.
They don’t have another god except ALLAH.
They don’t have another Prophet other than Muhammad.
They have the same five pillars of Islam(Testimonial, prayer, fasting,Charity Pilgrimage).
All of them pray in Arabic.
All of them face toward Makkah when praying .

Do all of Christian denominations follow the same god and books?

Islam is not part of Christianity. Christianity was built on crucifixon,and trinity .Which Muslim follow crucifixion and trinity?Islam emphasis oneness of God. We don’t even pray to Muhammad or his mother.