What is simple solution of uniting different sects in Islam?

There are many Muslims around the world who don't go into deep analysis of their religion, so they can easily be confused by different sects problem in Islam.

O you who have believed, obey Allah and obey the Messenger and those in authority among you. And if you disagree over anything, refer it to Allah and the Messenger, if you should believe in Allah and the Last Day. That is the best [way] and best in result.(Quran: Surah-An-Nisa, Verse 59)

This is a very simple solution provided by Allah almighty in Quran, so whenever we face any difference of opinion in anything, then we can easily resolve that issue be seeking what Allah and His prophet Muhammad (Peace be upon him) suggested.

Indeed, those who have divided their religion and become sects - you, [O Muhammad], are not [associated] with them in anything. Their affair is only [left] to Allah ; then He will inform them about what they used to do.(Quran: Surah-Al-Anam, Surah 159)

Prophet Muhammad (Peace be upon him) said: “My ummah will split into seventy-three sects, all of whom will be in the Fire except one sect.” They said: Who are they, O Messenger of Allah? He said: “[Those who follow] the path which I and my companions follow.” (Sunan-Tirmidhi -2641)