Judaea was converted into a Roman province in 6 A.D. The Jews, who found this situation unacceptable, started various rebellion movements against Roman domination, on religious and political grounds. As part of the rebellion movements, organized groups such as Sicarii and Zealots, and charismatic gang lords such as Simon ben Gioras and John of Giscala emerged. The main aim of these groups was to eliminate the Roman dominance, which they regarded to be illegitimate The Sicarii differed from the rebel groups of the period in terms of their activities and area of influence. So much that, the organization aimed to make God the sole ruler as well as ending the Roman domination. In this respect, they took on the Jewish leaders and especially the priesthood. In their actions, the Sicarii chose Jewish people collaborating with the Romans and Jewish people of priesthood aristocracy as their targets, rather than Romans. They have created an atmosphere of fear with their actions against these names and tried to impose their ideologies. The organization is considered to be the oldest known terrorist organization. Within the scope of the activities of these groups that were active during the 1st century, the Jews of the region suffered great challenge, and the sacred temple in Jerusalem was destroyed in the year 70. In this study, the ideology, actions and tactics of the Sicarii organization will be examined.