بسم الله المحد لله و صلاة و سلام على سيدنا نحمد و على آله و سلم تسليما
What constitutes a break-away sect? What are its signs and characteristics? There are many, but here I will quickly focus on one.
One of the major characteristics of a break-away sect is that they tend to focus on a particular aspect of a religion (ie details, secondary aspects) and as if it is a major, over-arching theme that defines the entire religion.
Case and Point: All Muslims believe in the Messiah, ‘Esa bin Maryam عليه السلام, and that another person named Imam Mahdi, will be his contemporary and both will come towards the very end of the time. However, this is an eschatological detail, not the central theme of the religion. But in the Ahmadiyya faith, this aspect is the single, central defining theme of the faith, such that even its website cites that they are:
In other words, in their declaration of being Muslims, they felt the need to simultaneously declare that particularity that separates them from the traditional, orthodox Muslim community.
Of course, all break-away sects also focus on the major aspects of their respective faiths. But, their insistence on a particular interpretation of a particular detail as the over-arching theme that is invariably divergent from the mainstream is a strong indication that they are a break-away sect.
Finally, such sects follow a common pattern. For the first few generations they are able to place special emphasis on their particular interpretation of the detail. After two or three generations the interpretation is retained, but adherents focus more on the major elements of the faith. After a few more generations the particular interpretation is completely de-emphasized except for cultural or social reasons, and shortly afterwards adherents are resorbed back into the original group.
May Allah guide us all to what is True
و صلى الله سيدنا محمد و على آله و سلم