Splitting up (tafarruq) is not from the Religion, because the Religion commands us with unity, and to be one jamāʿah (community), and one Ummah upon the ʿaqīdah of tawḥīd, and upon following the Messenger of Allāh (ṣallallāhu ʿalayhi wa-sallam).
An important set of questions and answers surrounding: the importance of ʿaqīdah, the harm of multiple Islamic groups (and movements), and the incumbency of following the manhaj of the salaf.