I hear people saying "I follow Maliki" or "I am Hanafi". Aren't we just all Muslims?
This question is frequently asked. So I just want to give a short point of view.
Yes we are all muslims, we are one in deen, one in aqidah. However, we are different in skin colors, races, languages, sexes (genders), cultures, environments, intelligence, ways of thinking, etc. Indeed it will be boring if there is no difference at all. Quoting Omar TV series, "We are different so that we need each other".
Talking about Maliki, Shafii, Hanafi, and Hanbali, they are all "schools" or method in research. It is a common thing in academic world to have different method and opinion as long as it is in scientific way; in this case based on Quran and Sunnah. Einsten could have opinion in General Relativity and others argue since there is no proof at the time. Some doctors or biologist could say MSG causes cancer etc and others argue since there is no enough proof. Even software developers have different opinions, there are "object-oriented madzhab" and "functional madzhab", there are "formal method madzhab" and liberal "agile method madzhab", there are "pro-documentation" fanatics and "self-documenting code" supporter, there are "verbose code madzhab" and "short concise code madzhab". I think it is only Mathematics which has no different opinion, because it can be proved in place.
وَلَوْ شَاءَ رَبُّكَ لَجَعَلَ النَّاسَ أُمَّةً وَاحِدَةً ۖ وَلَا يَزَالُونَ مُخْتَلِفِينَ
And if your Lord [Allah] had willed, He could have made mankind one community; but they will not cease to differ.
إِلَّا مَن رَّحِمَ رَبُّكَ ۚ وَلِذَٰلِكَ خَلَقَهُمْ ۗ ...
Except whom your Lord has given mercy, and for that He created them. ...
(QS. Hud: 118-119)
As Muslims we're told to strive for the truth and sometimes when striving for truth and analyzing Islamic texts to form a view, there is difference in opinion (based on differing understandings). So there are 4 major schools of thought in Islam. The Hanafis, Hanbalis, Malikis and Shafi'is.
All of those who adhere to these different groups are Muslims, and the different opinions do not divide them. (How could they when none of them differ on fundamentals of the religion, all united upon Tawheed and truth?). They only differ on minor rules of jurisprudence, etc. But firmly all hold to the rope of Allah (ﷺ).
So yes, we're all Muslims.