Iain Murray on the Sincerity of God's Offer

Finally, we can observe that the sincerity of God's offer even to the non-elect is in accordance with the truth that God does desire, delight and approve of things which, for other reasons, He has not determined to carry into effect. This distinction can be illustrated from God's commandments. His commandments express what He desires should be done. When the Israelites disobeyed them He cries–"O that my people had hearkened unto me." "O that thou hadst hearkened to my commandments! then had thy peace been as a river . . ." (Psa. 81:13; Isa. 48:18; Deut. 5:29). Unmistakably such verses express what was God's desire. Yet we must say that though their actions were, in their own nature, displeasing to God, He had nevertheless willed and permitted such conduct for wise and holy ends. Similarly with the Gospel offer. God desires that everyone should believe it; He has no pleasure in the death of the wicked (Ezek. 33:11) but delights in their conversion¹–thus Christ yearned for the salvation of the people of Jerusalem (Matt. 23:37). Yet this desire, in the case of the non-elect, is for the fulfillment of something which in His inscrutable counsel and sovereign purpose He has not actually decreed to come to pass. This distinction between God's desire and His will, or, more correctly stated between the will of God's benevolence and His decretive will, underlies the free offer of the Gospel.² His benevolence and compassion, expressed in the universal call to repentance, extend to every creatures whom He has not decreed to save. At this mysterious evidence of the unsearchable character of God's ways the humble believer stops and says with Calvin "we go no farther than the Lord leads us by his Word."
_______________
1. "God delights in the conversion and eternal life of the sinner, as a thing pleasing in itself, and congruous with his infinitely compassionate nature, and therefore demands from man as a duty due from him to turn if he would live."–Francis Turretin (1623–1687), Professor of Theology at Geneva. Quoted in W. G. T. Shedd's Dogmatic Theology, vol. II, p. 483 (1889 edit.).

2. This distinction may be a new one to many readers but it is far from novel. Calvin, in expounding 2 Peter 3:9 (God is "not willing that any should perish"), distinguishes between God's wish or revealed will and His determinate (hidden) purpose in the following words: "But it may be asked, If God wishes none to perish, why is it that so many perish? To this my answer is, that no mention is here made of the hidden purpose of God, according to which the reprobate are doomed to their own ruin, but only of his will as made known to us in the Gospel. For God there stretches out his hand without a difference to all, but lays hold only of those, to lead unto himself, whom he has chosen before the foundation of the world." Commentaries on The Catholic Epistles, p. 419.

Iain H. Murray, "The Free Offer of the Gospel: Viewed in the Light of the Marrow Controversy," Banner of Truth 11 (June 1958): 13–14.