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.
Judaism
Like the Sadducees who relied only on the Torah, some Jews in the 8th and 9th centuries rejected the authority and divine inspiration of the oral law as recorded in the Mishnah (and developed by later rabbis in the two Talmuds), relying instead only upon the Tanakh. These included the Isunians, the Yudganites, the Malikites, and others. They soon developed oral traditions of their own, which differed from the rabbinic traditions, and eventually formed the Karaite sect. Karaites exist in small numbers today, mostly living in Israel. Rabbinical and Karaite Jews each hold that the others are Jews, but that the other faith is erroneous.