In Colossians 2:20-23, Paul teaches that the denial of the flesh does not necessarily decrease the power nor the attraction of the flesh. Simple denial, he says, for its own sake profits nothing – not the flesh, not the spirit. It merely leads to pride.

With asceticism (severe restriction of the body's appetites) the spirit gains no insight, no greater knowledge of God's will or purpose for one's life or life in general. Many religions use this tactic (e.g. Buddhists) but have not discerned God's revelation through it, only what Paul calls,

…the appearance of wisdom in self made religion…
- Col. 2:23

Self-denial within Christianity, however, is the denial of sinful desires, not legitimate ones like, food, comfort, or intimacy. This type of denial (of sin) does profit the spirit and the flesh if done in Christ.

When we deny the temptation to sin, we provide a witness that our faith is true and demonstrate the power of the Holy Spirit within us. We also give a lost world a glimpse of what the kingdom of heaven will be like when Jesus returns.

So let's not be taken in by the pretensions of false religions that make the debasing and rough treatment of the body a key to spiritual power and insight. Let us rather witness to the Light by denying ourselves the works of darkness that tempt us each day.