This book is a printed edition of the digital series "Theology in Public". This series intends to present some basic texts from Saints of the ancient Church. It is an attempt to reveal the Christians the roots of their faith by presenting these texts in a simple language and an approachable way. Actually, these presentations are not a translation of the specific texts. They are patristic courses, taken place in the Aristotle University of Thessaloniki. I hope to expand the contribution of academic theology from the universities to the Christian community, making the lives, works, and thoughts of these Saints available to all. CONTENTS 1) GREGORY THE THEOLOGIAN BASIL'S FUNERAL ORATION 2) BASIL THE GREAT BE MINDFUL OF YOURSELF IN ORDER TO BE MINDFUL OF GOD 3) GOD AND THE EXISTENCE OF EVIL JOHN CHRYSOSTOM ON THE DEVIL 4) GOD AND MAN IN CHRIST. CYRIL OF ALEXANDRIA THAT CHRIST IS ONE