Distinguishing between splitting (iftiraaq) and differing (ikhtilaaf) is an extremely important matter. It is essential that such an issue be referred back to the people of knowledge, since most people – especially some of the callers to Islam (du’aat) and some of the students of knowledge who have not fully matured in their understanding of the Religion – do not make a distinction between issues of differing and issues of splitting. Because of this, some of them apply the ruling of splitting to issues of differing; and this is a dreadful mistake! The root cause of this is ignorance of the fundamental principles governing matters of splitting; when and how it occurs, and who decides if and when it is allowed to split away from a particular individual or group.
It is essential, therefore, to mention the distinctions between splitting and differing. Five such distinctions shall be mentioned by way of example, not that they are the only points of distinction:
The First Distinction: That splitting (iftiraaq) is a severer form of differing (ikhtilaaf), rather it is the consequence of differing because differences of opinion may or may not lead to the bounds of splitting. However, splitting is actually differing plus more, though not every differing is splitting – a point which forms the basis for the second distinction.
The Second Distinction: Not every issue of differing is an issue of splitting, though every splitting is differing. Indeed, many of the issues about which the Muslims dispute are actually issues of differing, Therefore it is not permitted to apply the ruling of disbelief upon those who differ, nor the ruling of splitting from them, nor the ruling of expelling them from the fold of the Sunnah.
The Third Distinction: That splitting (iftiraaq) only occurs in the great fundamentals (usool kubraa); those fundamentals of the Religion in which there is no scope for differing; those issues that have been established by a definite (qat’ee) text, or by a scholarly consensus (Umaal, or for which the scholars of AhlusSunnah wal Jamaa’ah have undertaken a thorough evaluation and do not differ about its conclusion. So whatever is like this is considered to be a fundamental precept (asl) and the one who opposes it is considered to have split away. Whatever else is besides this, then it enters into matters of differences. Thus differing (ikhtilaaf) occurs in issues other than the fundamentals; issues which are open to a number of opinions, open to ijtihaad, open to the possibility of being applied to any of the opinions; for which the one holding a view has some justification to do so, or due to the possibility of a lack of knowledge, coercion or mistaken interpretation. So all of this is in matters of ijtihaad and subsidiary issues (furoo). Differing can also occur in certain subsidiary matters that are connected to the actual fundamentals themselves, for which the holder of such a view can be excused due to a justified excuse, as determined by the reliable scholars of the Religion. These subsidiary issues may even be in matters of beliefs (‘aqeedah), about which there is an agreement upon its fundamentals, but in which there is a difference of opinion in some of its details; such as the consensus of the scholars concerning the occurrence of the Night Journey and Ascension (al-israa wal-miraaj), but their differing about whether the Prophet sallallaahu alayhi wa sallam saw His Lord with his eyes or his heart.
The Fourth Distinction: That differences may at times be the result of ijtihaad and good intentions – and providing he is endeavouring to seek the truth, such a person is rewarded even if he is mistaken. Although the one who is correct receives a greater reward, but the one who errs is still commended for his ijtihaad. However, if the issue reaches the level of splitting, then it becomes totally blameworthy. Splitting is never due to ijtihaad and good intentions and its proponent is never rewarded, rather he is censured and sinful in all cases. Therefore, splitting does not occur except due to innovations, or following whims and desires, or due to the blameworthy type of imitation (taqleed madhmoom).
The Fifth Distinction: That splitting is connected with a Divine threat (wa’eed) and all its forms lead to deviation and destruction. But this is not the case for differing, no matter how intense the differing may become between Muslims – as long as it is an issue in which ijtihaad is allowed. As for the one who holds a differing view, then it may be that he has some justification for his stance; it may be due to him being unaware of the proofs, or because of being compelled and no one else knows about this compulsion, or due to a mistaken interpretation which does not become evident to him until after the proofs have been established to him.
Source: General Precepts of Ahlus-Sunnah Wal Jamaa’ah by Naasir Bin Abdulkarim al-Aql, P. 27-28