Q: Dear Father Fortea, do demons experience time like we do?
A: Yes, in a sense. As pure spirits, angels and demons exist outside of earthly, material time. However, they do experience a type of “spiritual” time—“a before and an after” to their acts of understanding and will. Whenever we speak of “before” and “after,” we are speaking of some sort of time. This time is called aeveternal (from the Latin aevum), a succession of acts of understanding and will in a spiritual being. (St. Thomas Aquinas in the thirteenth century speaks about aevum in the Summa Theologica, I, 10, 5.)
Therefore, when we say that the spirits in heaven and hell are in “eternity,” we need to understand this as an unending temporal succession (i.e., the passing of time without end) from a distinct beginning (i.e., the moment of their creation). Strictly speaking, only God is eternal; only He has “no time.” God experiences past, present, and future as eternally present.
To learn more about spiritual warfare and demonology, Catholic Spiritual Direction recommends Fr. Fortea’s excellent book, Interview With An Exorcist – An Insider’s Look at the Devil, Demonic Possession, and the Path to Deliverance.