'Of the Flesh' in the Bible

Now I Paul, myself, appeal to you by the humble-heartedness and selflessness of Christ??aul who "in your presence is humble, but bold enough when he is absent"??2 I beseech you, and I say, do not make me show my boldness, when I come in the boldness with which I think I shall show my courage against some who think that I am walking on the low level of the flesh.

Though I do walk on the low level of the flesh, I do not make war as the flesh does;

for the weapons of my warfare are not weapons of the flesh, but mighty for God, in pulling down all fortresses.