The flesh,' as Saint Paul used the term, refers, ironically, not to our bodies but to fallen human nature. The 'carnal' spirit is the one that devours things for itself and refuses to make them an oblation to God. The carnal spirit is cruel, egocentric, avaricious, gluttonous, and lecherous, and as such us fevered, restless, and divided. The spiritual man, on the other hand, is alone the man who both knows what flesh is for and can enter into its amplitude. The lecher, for example, supposes that he knows more about love than the virgin or the continent man. He knows nothing. Only the virgin and the faithful spouse knows what love is about. The glutton supposes that he knows the pleasures of food, but the true knowledge of food is unavailable to his dribbling and surfeited jowls. The difference between the carnal man and the spiritual man is not physical. They may look alike and weigh the same. The different lies, rather, between one's being divided, snatching and grabbing at things, even nonphysical things like fame and power, or being whole and receiving all things as Adam was meant to receive them, in order to offer them as an oblation to their Giver.
Thomas Howard, Evangelical is Not Enough: Worship of God in Liturgy and Sacrament
flesh, human-nature, sin, spiritual-life