Both angels and demons are ignorant of the future, yet they make predictions. The angels do so when God reveals the future to them and commands them to prophesy, and what they prophesy comes to pass. Demons also make predictions, but these are only guesses based on what they see from afar.
John of DamascusAngels are intelligent reflections of light, that original light which has no beginning. They can illuminate. They do not need tongues or ears, for they can communicate without speech, in thought.
John of DamascusO Mother of God! If I place my confidence in thee, I shall be saved; if I am under thy protection, I have nothing to fear; for the fact of being thy client is a possession of a certainty of salvation which God grants only to those whom He intends to save.
John of DamascusThe whole earth is a living icon of the face of God. ... I do not worship matter. I worship the Creator of matter who became matter for my sake, who willed to take His abode in matter, who worked out my salvation through matter. Never will I cease honoring the matter which wrought my salvation! I honor it, but not as God. Because of this I salute all remaining matter with reverence, because God has filled it with his grace and power. Through it my salvation has come to me.
John of DamascusAn angel is an intelligent essence, always in motion. It has free will, is incorporeal, serves God, and has been bestowed with immortality. Only the Creator understands its true nature.
John of Damascus