Jesus in the Talmud
In the first few centuries CE, there were many sects of Judaism (such as Pharisees, Essenes, and Sadducees) each claiming to be the correct faith. Some scholars treat Christianity, during that era, referred to as Early Christianity, as simply one of many sects of Judaism. Some sects wrote polemics advocating their position, and occasionally disparaging rival sects. Some scholars view the depictions of Jesus in the Talmud as a manifestation of those inter-sect rivalries – thus the depictions can be read as polemics by the rabbinic authors of the Talmud which indirectly criticized the rival sect (Christianity), which was growing and becoming more dominant.
Islamic schools and branches
Shia Islam, on the other hand, is separated into three major sects: Twelvers, Ismailis, and Zaydis. The vast majority of Shias are Twelvers (a 2012 estimate puts the figure as 94% of Shias being Twelvers) to the extent that the term "Shia" frequently refers to Twelvers by default. The Twelver Shias are also notably the only sect of Muslims that complies with the saying of Muhammad that he would have twelve successors, a saying accepted by both Shia and Sunni Muslims.