Phil3:3 For it is we who are the circumcision, we who serve God by his Spirit, who boast in Christ Jesus, and who put no confidence in the flesh—NIV
When you look at the Christian race, it is a battle between the flesh and the Spirit. Two different forces are trying to gain control over us and who dominates our lives is simply a function of who we yield ourselves to. When we yield to the Spirit, we become spiritual and when we yield to the flesh, we become carnal.
It is possible to be in the Spirit this moment and in the next moment be in the flesh. Some believers are trying to attain spirituality with fleshy confidence. In fact, when you put your confidence in the flesh you'll fall into sin. I heard of a brother that boasted that if he sees a fair naked lady, he won't fall. The devil set a trap for him with a fair sister and he fell. Spiritual people don't boast about such things.
Confidence in the flesh can disgrace any man and disconnect from grace. The Jews were trying to please God and attain to righteousness by the law through confidence in fleshy observance, but Paul said those of us that born of the Spirit put no confidence in the flesh to please God because our circumcision is not of human hands but by the Spirit.
Submitting to the leading of the Spirit is a proof that we put no confidence in the flesh.
Father, I receive grace not to put my confidence in the flesh In Jesus name. Amen