Very true..but it is such a subtle thing..this self-effort in the flesh....it is massively deceptive.... as this quote that FreeNChrist showed us..talks about.
You may have harnessed the energy of the flesh in an otherwise quite genuine desire to honor the Lord Jesus in your life. The flesh, which has its origin in Satan, will go along with you; to survive, it is quite prepared to engage in every form of Christian activity, even though this may seem to honor Christ.
The flesh will sing in the choir, teach Sunday school, preside at a deacons’ meeting, preach from the pulpit, organize an evangelistic crusade, go to Bible college, volunteer for the mission field, and a thousand other things, all of which may in themselves be otherwise legitimate, if only it can keep its neck out of the noose. T
he flesh will threaten, shout, strut, domineer, sulk, plot, creep, beg, plead, or sob, whatever the situation may demand in the interests of its own survival. By any and all means it will seek to cause every Christian to live by his own strength instead of by the power and grace of the Lord Jesus, and to conclude that doing so is actually a good thing!
The characteristic of the spiritually immature is that they are unable to discern between good and evil (Hebrews 5:13-14), and the baby Christian, like the foolish Galatians, “having begun in the Spirit” still tries to be “made perfect by the flesh” (Galatians 3:3).
We must be particularly patient with those whose lack of understanding allows a genuine love for the Lord Jesus to be satisfied with, and sometimes to be quite enthusiastic about, Christian activities involving means and methods which are heavily contaminated by the flesh. These are more deserving of instruction than rebuke, for they are still in their spiritual babyhood.
.....The flesh will seek to produce the most plausible arguments in justification of its own illegitimate activities, even though these activities are only what the Bible calls “dead works” (Hebrews 6:1; 9:14) and not the “good works” which are truly the work of God. “Good works” are those that have their origin in Jesus Christ, as Christ’s activity is released through your body because you present it to Him as a living sacrifice. You do this only by faith that expresses total dependence, as opposed to Adamic independence."
Major Ian Thomas: The Way Of The Flesh; from The Indwelling Life of Christ