God likes to remind us of what we are in and of ourselves in order to keep us from being dependent on ourselves and our own works: “For ye see your calling, brethren, how that not many wise men after the flesh, not many mighty, not many noble, are called: but God hath chosen the foolish things of the world to confound the wise; and God hath chosen the weak things of the world to confound the things which are mighty; and base things of the world, and things which are despised, hath God chosen, yea, and things which are not, to bring to nought things that are: that no flesh should glory in his presence…that, according as it is written, He that glorieth, let him glory in the Lord.” 1 Corinthians 1.26-31
In order to keep us from patting ourselves on the back, God gives reminders ie. our failures, to show just how little we ought to esteem ourselves and our service to Him.
The sufficiency of God’s grace may not have been seen in Paul’s deliverance from the affliction, but it was wonderfully displayed in so far as the affliction had God’s desired effect upon Paul’s heart:
2 Corinthians 12.9, “Most gladly therefore will I rather glory in my infirmities, that the power of Christ may rest upon me.”
It is by understanding and applying these things, that we prove this doctrine and give glory to God.