For though we walk in the flesh, we do not war after the flesh (2 Corinthians 10:3 KJV)
Paul says though we walk or live in the flesh, we do not wage our war after the flesh. He makes a difference between walking in the flesh and warring after the flesh. It is the same as stating there is a difference between living in the flesh and living after the flesh.
It may sound a little strange for some of you to read that we are walking or living in the flesh because we know we should be walking in the Spirit. This is where context matters in the correct interpretation of scriptures. Living in the flesh, as used here, means being alive here on the earth, with a spirit, soul and body. The flesh is not evil in itself in this sense. It simply means our earthly existence. The Word became flesh and lived in the flesh amongst the disciples!
However, though we are living in the flesh, we do not war or fight our battles after the flesh. We do not use human means to fight our battles. We do not fight against people but against spirits. We use salvation, righteousness, truth, faith, the Word of God and even love to fight our battles. These do not make sense to ordinary people. It should not because they are not fleshly, but divinely given weapons!
What is the difference between living in the flesh and walking in the flesh? Think of a battle you are currently engaged in right now; maybe someone just offended you. You will either do what normal humans do( according to the flesh) such as retaliate or bear a grudge or respond according to the Spirit( in love, etc).
APPLY THE WORD
You are living in the flesh but called to live after the Spirit. Guide your heart, actions, and words by the dictates of the Spirit.
Ask the Spirit to help you become steadfast in walking the Spirit while living at the same time in the flesh.