Is it possible for a Muslim to not identify himself/herself belonging to any sects? If so, how does s/he chose what to believe on the controversial (different sects have different opinions) topics.
Meaning of the Hadith about the 73 sects in Islam
This is the Hadith
Dawud :: Book 40 : Hadith 4579
The Prophet (peace_be_upon_him) said: The Jews were split up into seventy-one or seventy-two sects; and the Christians were split up into seventy one or seventy-two sects; and my community will be split up into seventy-three sects.
Here Prophet Muhammad (PBUH) says that his Ummat (community) will be divided. He never told us to divide. This is one of our misconceptions that "He told us to divide so we are dividing".
From this hadith we must make it clear that he never supported division amongst muslims he just predicted that something like this will happen.
Verses from the Quran that prove making sects is bad
Allah has written in the Quran -
And hold firmly to the rope of Allah all together and do not become divided. And remember the favor of Allah upon you - when you were enemies and He brought your hearts together and you became, by His favor, brothers. And you were on the edge of a pit of the Fire, and He saved you from it. Thus does Allah make clear to you His verses that you may be guided. [3:103]
Here Allah says not to get divided.
Allah says in another verse -
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. [6:159]
Here Allah says to Prophet (PBUH) to not to worry about people who make sects and that He himself will handle them.
Allah also says more about these people who create sects -
And indeed, there is among them a party who alter the Scripture with their tongues so you may think it is from the Scripture, but it is not from the Scripture. And they say, "This is from Allah ," but it is not from Allah . And they speak untruth about Allah while they know.[3:78]
Here Allah is saying that there will arise people who will misinterpret the Quran and tell it is word from God. Here Allah is pointing out to those who make sects and then justify the rightness of the sect.
I do not agree with following any sect.
Always follow the word of Allah i.e. the Quran and The Sahih Hadeeths. If someone tells you something not there in these two places just disregard them.
Also call yourself none but a Muslim as stated in the following verse -
Say, "O People of the Scripture, come to a word that is equitable between us and you - that we will not worship except Allah and not associate anything with Him and not take one another as lords instead of Allah ." But if they turn away, then say, "Bear witness that we are Muslims [submitting to Him]."[3:64]
Hope Allah guides you onto the right path. Ameen.
(This is a Shia view)
Firstly please note this Hadith of Prophet Muhammad (PBUH):
the Judaism nation after Moses (PBUH) became 71 sect that 70 of them are in Hell and 1 in Heaven and Christianity nation after Jesus (PBUH) became 72 sect that 71 of them are in Hell and 1 in Heaven and Islam nation after prophet become 73 sect that 72 of them are in Hell and 1 in Heaven.
And We have revealed to you, [O Muhammad], the Book in truth, confirming that which preceded it of the Scripture and as a criterion over it. So judge between them by what Allah has revealed and do not follow their inclinations away from what has come to you of the truth. To each of you We prescribed a law and a method. Had Allah willed, He would have made you one nation [united in religion], but [He intended] to test you in what He has given you; so race to [all that is] good. To Allah is your return all together, and He will [then] inform you concerning that over which you used to differ. [5:48]
Also Quran says:
[6:159] 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.
But if sect means following a right path or group, then there's really nothing wrong with it. Quran explicitly talks Ibrahim S.A. was a follower of Muhammad.
[37:83] And indeed, among his followers was Abraham,
So generally it is intuitive that division of Ummah is an ominus phenomena according to Quran and the Prophet, but finally there has to be only one sect out of 73 sects of Muslims that is exactly identical to the original and authentic religion of Prophet. So belonging to a sect is not prohibited if that sect really represents true Islam.
It is also intuitive that no Muslim wants the Ummah to be divided. As Quran says we should:
[3:103] hold firmly to the rope of Allah all together and do not become divided. And remember the favor of Allah upon you - when you were enemies and He brought your hearts together and you became, by His favor, brothers. And you were on the edge of a pit of the Fire, and He saved you from it. Thus does Allah make clear to you His verses that you may be guided.
But finally we are facing the reality and should accept the facts. The fact is that shia Muslims believe that Imamate (spiritual-political leadership of Ummah after prophet) is part of and one of the pillars of Islam with which religion was brought to perfection, whereas Sunnis believe that Imamate is not part of Islam. Can a Muslim really follow none of these two positions? He can't responsibly stay neutral on a question of such importance to religion, and finally he has to adhere to one of them and that makes him part of one sect. This is not the labels that are really important in the way that a sect is defined by its distinct beliefs and not by what we call ourselves. So if a sect can prove its full adhere to the religion of Prophet, then that would render it as the true Islam, not a misled deviant sect.
"sect" is a vague word.
One meaning is to divide Muslims into groups unfriendly to each other. Quran objects to it. As I understand, from Quran's perspective anyone who believes (a state of heart) in God and the Judgement day and does good deed is a believer all believer are spiritual brothers/sisters.
Another meaning, which I think is sometimes more applicable, is "a school of thought in Islam". There is no decree forbidding belonging to a school of thought. Almost every person belongs to some school of thought (even Salafies who insist on just being pure Islam). By itself it is not problematic. One group believes that we close our hands when praying, another one believes the hands should be left straight, etc. These differences should not lead to enmity. Each have their opinion and they have justification for them and as Quran says God will judge about those disagreements of opinion. Quran calls for unity among Muslims, some view this as a justification to unify by force everyone to believe in exactly the same things and act exactly in the same manner, but in reality that does not lead to unity but division, unity cannot exist without tolerance towards others.
It is possible to not to follow any major school of thought in Islam but in reality it is difficult.
Now can one refer to oneself as a follower of one school? It can be fine. We have various identities based on our sex, race, skin color, nationality, language, culture, belong to a tribe, etc and Quran doesn't view them negatively, e.g. see verse 49:13. You can identify with a school of thought as you identify with some other attributes. These are not problematic by themselves. The problem starts if these identities start to act against the general brotherhood/sisterhood among Muslims that I mentioned above. If you feel hate towards other Muslim groups because of difference in these identities between you and them then it is problematic.