In theology, it refers to the belief that God is present by His Essence everywhere and in all things by reason of His Immensity. Furthermore, it also refers to the belief that God is in an special manner really and substantially present in the souls of the just.
In devotion, to put oneself in the presence of God, or to live in the presence of God, as spiritual writers express it, means to become actually conscious of God as present, or at least so to live as though thus actually conscious. Also, the devout soul may be mindful of His Presence in another way, namely, by the exercise of reason directed by faith. He sees God in the earth, the sea, the air and in all things; in heaven where He manifests His Glory, in hell where He carries out the law of His Justice.