On January 30th, the Orthodox Church celebrates the Three Holy Hierarchs: Basil the Great, Gregory the Theologian, and Ioannis Chrysostom. All three were highly influential bishops of the early Church who played pivotal roles in shaping Christian theology and Greek education. The Three Saintly Hierarchs show how Christians can make use of education through their use of Hellenism. In recognition of the contribution of the Three Holy Hierarchs, in 1842, the University of Athens established the feast of the Three Holy Hierarchs as the day of celebration of the Greek letters to which Saints Basil, Gregory, and Ioannis gave prominence as an ecumenical treasure through study, research, and writing. Orthodox Church: The Main Differences