12:7-10 The apostle gives an account of the method God took to keep him humble, and to prevent his being lifted up above measure, on account of the visions and revelations he had. We are not told what this thorn in the flesh was, whether some great trouble, or some great temptation. But God often brings this good out of evil, that the reproaches of our enemies help to hide pride from us. If God loves us, he will keep us from being exalted above measure; and spiritual burdens are ordered to cure spiritual pride.
This thorn in the flesh is said to be a messenger of Satan which he sent for evil; but God designed it, and overruled it for good. Prayer is a salve for every sore, a remedy for every malady; and when we are afflicted with thorns in the flesh, we should give ourselves to prayer. If an answer be not given to the first prayer, nor to the second, we are to continue praying. Troubles are sent to teach us to pray; and are continued, to teach us to continue instant in prayer.
Though God accepts the prayer of faith, yet he does not always give what is asked for: as he sometimes grants in wrath, so he sometimes denies in love. When God does not take away our troubles and temptations, yet, if he gives grace enough for us, we have no reason to complain. Grace signifies the good-will of God towards us, and that is enough to enlighten and enliven us, sufficient to strengthen and comfort in all afflictions and distresses. His strength is made perfect in our weakness.
Thus his grace is manifested and magnified. When we are weak in ourselves, then we are strong in the grace of our Lord Jesus Christ; when we feel that we are weak in ourselves, then we go to Christ, receive strength from him, and enjoy most the supplies of Divine strength and grace.