Just to explain what "sunni" means...it comes from: Ahlus Sunnah wal-Jama'ah: "The Community that follows Mohammed's path, and general Consensus".
It's just the default state of being Muslim. So anyone who 'declined' having the progeny of Mohammed SAAW become leaders (turning Islam into some kind of aristocracy) is sunni...the ones who supported the "ahlul bayt" (Family of the prophet SAAW) becoming leaders were called "Shia't Ali" (The party of Ali). and they were always a minority.
Now to understand the way Islam sees the world you have to look at things from the Islamic lens. All the prophets/messengers in the scripture...Adam, Enoch, Noah, Abraham, Isaac, Ishmael, Jacob, Joseph, etc (AS), were Muslims. Why? Because they submitted to the will of Alla, and what they revealed, was the "Islam" of their time. So Moses' ten commandments was the Islam and Sharia of his time, the Injeel of Jesus AS was the Islam of his time, and Mohammed SAAW is the seal of the prophets. So just like the quran "abrogated alcoholic consumption in a gradual manner" within Mohammed's SAAW lifetime...Islam we have today is the 'final form' of the Islams from Adam-Eve's time, till the end.
That I am just a regular joe, but seen as an ambassador of Islam is telling...because the average Muslim regular joe, takes his religion "more serious" than even a Christian priest/bishop. I remember reading in Lutheranism, you can be an ordained minsiter and not even "believe in God". Im sorry I dont take (most) modern christian denomination seriously.
Judaism's "reform" branch is a christianization of Judaism.
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I dont consider Buddhism a religion with a 'creed (aqeedah)'..
Sikhism is just a Punjabi neo-hindu response to Afghan raids. Its not a serious thing. Will never be a world religion.
Hinduism is just what the British Admins labeled the indigenous beliefs that couldnt be classified as: Islam/Christian/Jewish/Buddhist/Jain/Sikh. You have monotheistic hindus and polytheists. Its not a serious "religion"
Taoism-Confuscianism: I dont know too much of it to have an opinion, but most Chinks today are atheists or born-again christian anyway