Adam Clarke on Galatians 5:17

For the flesh lusteth against the Spirit - God still continues to strive with you, notwithstanding your apostasy, showing you whence you have fallen, and exciting you to return to him; but your own obstinacy renders all ineffectual; and through the influence of these different principles, you are kept in a state of self-opposition and self-distraction, so that you cannot do the things that ye would. You are convinced of what is right, and ye wish to do it; but, having abandoned the Gospel and the grace of Christ, the law and its ordinances which ye have chosen in their place afford you no power to conquer your evil propensities. It was on this ground that the apostle exhorted them, Gal 5:16, to walk in the Spirit, that they might not fulfill the lust of the flesh; as without the grace of God they could do nothing. Who can suppose that he speaks this of adult Christians?