In Christian theology, the world, the flesh, and the devil (Latin: mundus, caro, et diabolus; Greek: ό κοσμος, ή σαρξ, και ό διαβολος) have been singled out "by sources from St Thomas Aquinas" to the Council of Trent, as "implacable enemies of the soul".
Peter Abelard states in his Expositiones that: Tria autem sunt quae nos tentant, caro, mundus, diabolus ("There are three things which tempt us, the flesh, the world, and the devil").
[8]The phrase may have entered popular use in English through the Book of Common Prayer, which includes in its Litany: "[F]rom al the deceytes of the worlde, the fleshe, and the deuill: Good lorde deliuer us."
[9] John of the Cross cites the world, the flesh, and the devil as threats to the perfection of the soul, and offers different "precautions" to be taken against each of these.
The question of whether the world and the flesh are inherently bad and what the individual's proper relationship to them ought to be has long been debated in many philosophical and spiritual traditions.