Do all Muslims believe the same thing?Unlike Christianity basic beliefs of Islam are same. All Muslims shiites or mainstream Muslims believe that Allah is One and Only Creator and Muhammad(SAW) is His last prophet and Quran is His last and final book from Lord of the multiverse. Shiites say hazrat Ali who was first cousin of prophet Muhammad should have been appointed his successor, but mainstream Muslims think what happen was right according to caliphate rules.
Yes, all true practising Muslims believe the same thing!
The faith is based on Allah (The One True God) and Hereafter (answering for the deeds in the after life)
Believeing in Quran, sahih Hadith
and there are more!
I will post a video , from where you can know about the basic beliefs of a Muslim
watch from the series : [short clips]
1. Faith 2. Quran Hadith 03. The Messengers of the God 04. Jannah and Jahannam 05. Qadr 08. Shirk 09. Tawbah
Here's Shaykh Hamza Yusuf writing on the topic:
"Umar ibn Abdul Aziz said "I am glad that the companions of the Prophet (sallallahu 'alayhi wa sallam) did not agree on everything". He said the meanings of that is when you have differences of opinions, it makes things broader and so that people can have more flexibility in their religion. Because when there is an ijmaa about something then everybody is forced to follow that opinion because there has been no dissent." - See more at: Page on shaykhhamza.com