The Battle Within: The Flesh vs. the Spirit

The Christian life is becoming what you already are in Christ. Like a new creation already begun, but not yet complete (BOK Post 11), your struggle against sin is real even as the Spirit works to transform you.
An enemy that lives off what you keep feeding it will only grow stronger. As long as we keep the door open and supply what the flesh craves, we shouldn't be surprised when it takes over. The strategy is simple but costly: make yourself uninhabitable to it. Stop giving it what it wants. Starve it.
In New Testament thought, "the flesh" is not just the physical body — it is any thought pattern, appetite, vanity, or predilection that opposes God's will. "For to set the mind on the flesh is death, but to set the mind on the Spirit is life and peace. For the mind that is set on the flesh is hostile to God" (Rom 8:6–7). We keep giving our flesh what it wants — and we shouldn't be surprised when it grows stronger.
The Christian's motivation to resist the flesh is not fear of punishment — salvation is settled (Eph 2:8–9). It is love and allegiance to your King. We are called to imitate Jesus because we love him and are united with him. "Have this mind among yourselves, which is yours in Christ Jesus" (Phil 2:5).
By the Spirit's power, 'walk by the Spirit' (Gal 5:16) and you will not gratify the desires of the flesh. The Spirit enables you to resist the flesh, and the result will be His fruits: love, joy, peace, patience, kindness, goodness, faithfulness, gentleness, and self-control. Live out your new identity in Christ by allowing the Spirit to starve the flesh and cultivate these fruits in you.