SHAYKH 'ABDUL-'AZEEZ BIN BAAZ
[Q]: What is the obligation upon the Muslim Scholars with regard to the large number of jam'iyyaat (societies) and jamaa'aat (groups) in many of the Islaamic lands and elsewhere, and with regard to the differences that exist between them, to the point that each group declares the others to be misguided. Do you not hold that it is fitting to enter into explaining the like of this matter, and to clarify the truth concerning their differences, for fear that these differences will increase and lead to evil consequences for the Muslims?
[A]: "Our Prophet made clear to us a single way which it is obligatory upon the Muslims to follow and traverse, and that is Allaah's Straight Path and the methodology of His upright religion. Allaah - the Most High - said: "And this is My Straight Path, so follow it and do not follow other paths that will separate you from His Path. This has He ordained for you, that you may become pious." [Surah Al-An'am Verse 153]. Just as the Lord of Might and Majesty warned the Ummah (nation) of Muhammad against splitting and disunity, since that is one of the greatest causes of failure and of the enemy taking control, as occurs in the saying of Allaah - the Mighty and Majestic's: "And fold fast altogether to the rope of Allaah and do not be divided." [Surah Aali Imran Verse 101]. And His - the Most High's - saying: "He has ordained for you the same religion which He ordained for Nooh, and that which We revealed to you, and that which We ordained for Ibraaheem, Moosaa and 'Eesaa 'alayhimus-salaam, saying: that you should establish the religion by doing that which you are ordered with, and make no divisions in it. Intolerable for the Pagans is that to which you call them." [Surah Ash-Shura Verse 13]. So this is a Divine call to unity and for hearts to be harmonized. And in any Islaamic land, if there are many groups for the purpose of good, aid, co-operating in righteousness and piety between the Muslims - without their being differences between the desires of the companions and followers - then this is good, is a blessing, andd produces great benefit.
However, if each of them declare the others to be misguided and attack their actions, then this harm is very great and its evil consequences very serious. Then what is obligatory upon the Muslims is to clarify the true state of affairs and to discuss with each group and to sincerely advise all of them that they should proceed upon the way laid down by Allaah for His servants, and upon that which our Prophet Muhammad called to. Then those who ignore this, or continue in their stubbornness, due to personal benefit or goal - known only to Allaah - then what is obligatory upon those who know the reality is to make this known about them and to warn against them, so that the people may avoid their path, and that those who do not know the reality of their affair may not fall into it and be led astray, and that they are not turned away from the Straight Path which Allaah ordered that we follow, as occurs in His - the Mighty and Majestic's - saying: "And this is My Straight PPath, so follow it and do not follow other paths that will separate you from His Path. This has He ordained for you, that you may become pious." [Surah Al-An'am Verse 153]. And from that which there is no doubt about is that the multitude of sects and groups in the Islaamic society is, firstly something desired by Shaytaan, and secondly something desired by the enemies of Islaam from amongst mankind. Since agreement and unification of the Muslims, and their being aware of the dangers which threaten them and their 'aqeedah (beliefs), will make them active in refuting and rebutting it, and acting in a unified manner for the benefit of the Muslims - thus repelling the danger from their religion, their lands and their brothers. And this is something which the enemies - from amongst mankind and jinn - are nnot pleased with. Therefore they are very eager to split-up the Muslims, destroy their unity and to sow the seeds of enmity and discord between them. We ask Allaah that He unites the Muslims upon the truth and that He removes from their society every type of misguidance and every cause of discord. Indeed He is the One Who is able to do that, and He is the One having full power over it." 
[Q]: ... and the students of knowledge refer back to you and to the other major Scholars and ask them. So what do you advise them? Do you advise and approve of entering (i.e. joining) the likes of these groups; such as Jamaa'atul-Ikhwaan, Jamaa'atut-Tableegh, Jamaa'atul-Jihaad, and so on, or do you advise them to remain upon seeking knowledge with the students of knowledge from those who call to the way of the Salaf (the Pious Predecessors)?
[A]: "All praise is for Allaah and may Allaah
extol and send blessings of peace upon His Prophet. We advise them all
to unite upon a single way and that is the way of seeking knowledge and
attaining understanding of the Book and the Sunnah, and to proceed along
the manhaj (methodology) of Ahlus-Sunnah wal-Jamaa'ah. I advise them all
that their goal should be to follow the Book and the Sunnah and to proceed
upon the manhaj of Ahlus-Sunnah wal-Jamaa'ah, and that they should all
call themselves Ahlus-Sunnah or the followers of the Salafus-Saalih (Pious
Predecessors). But as for tahazzub (bigotted partisanship) for the Ikhwaanul-Muslimeen,
or Jamaa'atut-Tableegh, or so on, then I do not advise that. That is a
mistake. Rather we advise them that they should be together upon a single
way, a single jamaa'ah, advising one another with the truth and having
allegiance to Ahlus-Sunnah wal-Jamaa'ah. This is the correct way to prevent
differences. But if there are various groups upon that same way (i.e. of
following the Salafus-Saalih) - a group in such and such a place, and another
in such and such a place - but all of them are upon the Salafee 
way, following the Book and the Sunnah, calling to Allaah and having allegiance
to Ahlus-Sunnah wal-Jamaa'ah - without tahazzub (partisanship) and without
ta'assub (bigotted blind-following) - then that is not harmful - even if
there are a number of groups - as long as their way and their goal is one."
SHAYKH SAALIH AL-FAWZAAN
[Q]: Noble Shaykh, with regards to the serious state in which the Ummah of Islaam lives - a state of confusion in peoples' thoughts - particularly in matter relating to the Religion. For the Islamic Jamaa'ahs (groups) and sects have become many, and each of them claim that their manhaj (methodology) is the correct Islamic methodology which must be followed. So the Muslim is left in a state of confusion as to what he should follow and which one is upon the truth.
[A]: "Splitting up is not from the Religion, since the Religion commands us with unity and that we should be a single Jamaa'ah and a single Ummah upon the 'aqeedah (belief) of Tawheed (i.e. to single out Allaah alone for worship) and upon following the Messenger . Allaah - the Most High - said: "Indeed this Ummah of yours is a single Ummah and I am your Lord, so worship Me alone." [Surah Al-Anbiya Verse 92]. And Allaah - the Most High - said: "And hold fast altogether to the rope of Allaah and do not become divided." [Surah Aali Imran Verse 103]. And Allaah - the Most Perfect - said: "Indeed those who split-up their Religion and become sects, you have no part with them in the least. Their affair is with Allaah who will tell them what they used to do." [Surah Al-An'am Verse 156]. So this contains a severe warning against splitting and differing. Allaah - the Most High - said: "And do not be like those who split-up and differed after the clear evidences came to them. For them is a tremendous punishment." [Surah Aali Imran Verse 105].
So our Religion is the Religion of al-Jamaa'ah, and the Religion of agreement and unity. Splitting is not from the Religion, since the Religion orders that we are a single Jamaa'ah and the Prophet said: "The Believer to the Believer is like a building, one part supporting the other."  And he also said: "The example of the Believers with respect to their mutual love, mercy and affection is like the example of a single body."  And it is known that a building and a body are a single cohesive thing, not disunited and fragmented - since if a building splits then it will collapse; and likewise a body, if it splits, then life will be lost. Thus, there must be a unity and we must be a single Jamaa'ah whose foundations is Tawheed and whose methodology is the da'wah (call) of the Messenger ; and which proceeds upon the Religion of Islaam. Allaah - the Most High - said: "And this is My Straight Patth, so follow it, and do not follow other paths that will separate you from His Path." [Surah Al-An'am Verse 153]. So these groups, and this splitting which is present today, is not approved of by Islaam. Rather, Islaam forbids it severely and commands uniting upon the 'aqeedah (belief) of Tawheed and upon the methodology of Islaam, a single Jamaa'ah and a single Ummah, just as our Lord - the Most Perfect, the Most High - ordered. And splitting and their being many (differing) groups and parties is from the plots of the devils - from the jinn and mankind - against this Ummah. So the kuffaar (disbelievers) and the munaafiqs (hypocrites) have never ceased, since olden times, introducing their poison in order to split the Ummah. The jews said previously: "And a party of the People of the Book say: Believe in the morning in that which is revealed to the Muslims, but reject it at the end of the day, so they may turn back." [Surah Aali Imran Verse 72]. Meaning: that the Muslims will leave their religion when they see you leaving it. And the Hypocrites said: "Do not spend on those who are with Allaah's Messenger until they desert him." [Surah Al-Munafiqun Verse 7]. "And as for those who erect a mosque by way of disbelief and seeking to harm and disunite the Believers ..." [Surah At-Tawbah Verse 107]." 
[Q]: What is the ruling with regards to those who align themselves with those jamaa'ahs, particularly those that are established upon secrecy and giving bay'ah (pledge of allegiance to the party leader)?
[A]: "The Prophet
informed us that splitting would occur and he ordered us, at that particular
time, to come together and to be upon that which the Messenger
and his Companions
were upon. So he
said: "The jews split-up into seventy-one sects and my Ummah would split-up
into seventy-three sects. All of them are in the Fire except one."
said: Who is it O Messenger of Allaah? So he replied: "That which I
and my Companions are upon this day."  And he
said, when his Companions
asked him to advise him: "I advise you to have taqwaa (fear and
obedience) of Allaah and to hear and to obey, even if an Abyssinian
slave is a leader over you. And those of you who live long after me will
see many differences of opinion. So hold fast to my Sunnah and the guidance
of the Rightly-Guided Khaleefahs (Successors) after me; cling to
it tightly ..."  So this is the manhaj (methodology)
which is obligatory for all the Muslims to follow, until the Day of Resurrection.
So when disagreements occur then they must return back to that which the
Salaf (the Pious Predecessors) of this Ummah were upon, with regards to
manhaj, bay'ah (pledge of allegiance), and other matter connected to the