Though we walk in the flesh - That is: Although I am in the common condition of human nature, and must live as a human being, yet I do not war after the flesh - I do not act the coward or the poltroon, as they insinuate. I have a good cause, a good captain, strength at will, and courage at hand. I neither fear them nor their master.
For though we walk in the flesh - Though we are mortal like other people; though we dwell like them in mortal bodies, and necessarily must devote some care to our temporal needs; and though, being in the flesh, we are conscious of imperfections and frailties like others. The sense is, that he did not claim exemption from the common needs and frailties of nature. The best of people are subject to these needs and frailties; the best of people are liable to err.
We do not war after the flesh - The warfare in which he was engaged was with sin, idolatry, and all forms of evil. He means that in conducting this he was not actuated by worldly views or policy, or by such ambitious and interested aims as controlled the people of this world. This refers primarily to the warfare in which Paul was himself engaged as an apostle; and the idea is, that he went forth as a soldier under the great Captain of his salvation to fight his battles and to make conquests for him. A similar allusion occurs in 2 Timothy 2:3-4. It is true, however, that not only all ministers, but all Christians are engaged in a warfare; and it is equally true that they do not maintain their conflict “after the flesh,” or on the principles which govern the people of this world. The warfare of Christians relates to the following points:
(1) It is a warfare with the corrupt desires and sensual propensities of the heart; with eternal corruption and depravity, with the remaining unsubdued propensities of a fallen nature.
(2) with the powers of darkness; the mighty spirits of evil that seek to destroy us; see Ephesians 6:11-17.
(3) with sin in all forms; with idolatry, sensuality, corruption, intemperance, profaneness, wherever they may exist. The Christian is opposed to all these, and it is the aim and purpose of his life as far as he may be able to resist and subdue them. He is a soldier enlisted under the banner of the Redeemer to oppose and resist all forms of evil. But his warfare is not conducted on worldly principles. Muhammed propagated his religion with the sword; and the people of this world seek for victory by arms and violence; The Christian looks for his conquests only by the force and the power of truth, and by the agency of the Spirit of God.