I think I need to explore my thoughts, Quran is the only unchangeable book in this world.
This is a miraculous gift for Muslims. It's each and every sentence is GREAT MILE STONE for every Muslims.
Muslims need to understand the messages and should obey line by line.
If they Follow Quran there is nothing Shia or Sunni there. Both two groups are misguided, they are third party, might not the follower of Islam or Quran.
Please judge the verse. Such other verses are in the Quran, Muslims ignoring them from their 1400 years or more.
"Do not be like those who after they have been given clear revelation, split into factions ad fall into disputes.: a terrible punishment awaits such people" (aL-Imran 105 verse). And do not become like those who have split up and differed after what had come in them of clear proofs. And these! for them there is a severe punishment" (Surah Al-Imran 104 verse).
In this regard present Muslims are deviate Muslim. Looked Muslim but internally they are not true follower. They need to turn back to their origin. Prophet Muhammad (s) and his four Khulaphaye Rashida were not shia or sunni, simply they were true Muslim followed real Islam, received true guidance. Allah the GREAT.