"But how do we wrong grace? I answer—five ways—
1. By neglecting the offers of grace. Such make God speak in vain, and to spend his best arguments to no purpose: 2 Cor. 6:1, 'We then, as workers together with him, beseech you also that ye receive not the grace of God in vain.' By the grace of God is there meant the offers of grace in the gospel. Now, we receive it in vain when all the wooings and pleadings of grace do not move us to bethink ourselves and look after our salvation. It is a great affront you put upon God to despise him when he speaks in the still voice. Look, as when David had sent a courteous message to Nabal, add he returns a churlish answer, it put him in a fury: 1 Sam. 25: 34, ' Surely there had not been left by the morning light any that pisseth against the wall.' So how angry will the Lord be against those that despise his grace, and all the renewed offers and messages of love, and prefer the profits and pleasures of the world before him. It may be you do not return a rough and churlish answer, and are not scorners and opposers of the word, but you slight God's sweetest message, when he comes in the sweetest and mildest way. The complaint in the gospel was, Matt. 11:17, ' We have piped unto you, and you have not danced.' It is not, We have thundered unto you, and you were not startled; but, We have piped, and ye have not danced. Not to take notice of these sweet allurements and blandishments of grace, that is very sad: Heb. 2: 3, ' How shall we escape, if we neglect so great salvation?' The greatness of the benefit aggravates the sin. It is great salvation that is offered; there is an offer of pardon and eternal life, but it worketh not if you neglect it. There is a sort of men that do not openly deny, reject, or persecute the gospel, but they receive it carelessly, and are no more moved with it than with a story of golden mountains, or rubies or diamonds fallen from heaven in a night-dream. You make God spend his best arguments in vain if you neglect this grace. Scourge conscience till it ache. What will you do? ' How will you escape, if you neglect so great salvation?' God sets himself a-work to gain the heart, and grace hath laid open all its treasures, as a man in a shop to draw in custom; now it is grieved and wronged when it doth not meet with a chapman. This is the charge that is laid upon those, Matt. 22: 6; when they were invited, ' They made light of it;' they did not take it into their care and thoughts, did not seriously think with themselves, Oh, that God should invite us to the marriage of his Son! They do not absolutely deny, but make excuse; they do not say, nonplacet, but non vacant—they are not at leisure; and this made the king angry. When all things are ready, and God sets forth the treasures and riches of his face, and men will not bethink themselves, their hearts are not ready. How will this make God angry? Such kind of neglecters are said to ‘judge themselves unworthy of eternal life,' Acts 13:46. You will say, Is there any fault in that? Who is worthy? Should we not judge ourselves to be vile forlorn creatures, unworthy of a look from God, much more of eternal life? I answer—It is not spoken of self-humbling, or of a holy self-condemning, but of those that turn their back upon grace. Grace comes to save them, and God makes them an offer as though they were worthy; and they judge themselves unworthy, and plainly declare they were altogether not worthy of this grace. All men are unworthy enough of eternal life, and God hath cause enough to condemn them ; but they chiefly judge themselves unworthy, that is, in fact declare themselves to be so, that have received the honour and favour of a call. Grace hath spoken unto them, and made them an offer of pardon and salvation, and they turn the back upon it, as if it were not worth the taking up on God's terms; and such are all ignorant sots and deaf worldlings."
"...but he is a profane man indeed that despiseth the gospel, because it offereth such an excellent salvation; that is profaneness, to slight God's best provision, to scorn his bowels, and, when the Lord hath made the bait an allurement so strong to gain man's heart, yet to turn his back upon it."
Thomas Manton, SEVERAL SERMONS UPON TITUS 2: 11-14 (Works, vol. 16, Sermon 1).
"[2.] The earth is the only place where this work is begun, or else it shall never be done hereafter: instance in anything that is the will of God. Here we must believe, or there we shall never enjoy: Luke ii. 14, 'Peace upon earth.' Now God offereth grace, and now it is his will we should come out of our sins, and accept of Christ to the ends for which he hath appointed him. And here we must be sanctified, else we shall be filthy for evermore. Corn grows in the field, but it is laid up in the barn. Now is the time of minding this work, here upon earth."