Angelology and demonology notions in Psalm 91 
Keywords:angelology, demonology, psalm, knowledge of God, communion
In this study, we wish to focus our attention on several concepts of angelology and demonology in the Book Psalms. In order to be as comprehensive as possible, we have chosen psalm 90 which emphasizes, in a unique manner, the battle between angels, which are messengers of God, and demons for the human soul. After the introductory elements, we will identify the passages which directly or metaphorically indicate the presence of unseen powers and the contact between those two opposing powers. In the second part of the study we’ll present some Patristic analyses by which we will highlight the way the Holy Fathers related to these texts, and finally; before the necessary conclusions, we will make a theological synthesis that emphasizes the part played by the devil in the human’s straying from God and the role that angels have in the life of a man who wants to approach and communicate with God.