This is a section from Thomas Watson’s book “All Things for Good” outlining how God works all things for good to believers, The promises of God:
The promises are notes of God’s hand; is it not good to have security? The promises are the milk of the gospel; and is not the milk for the good of the infant? They are called ‘precious promises‘ (2 Pet. 1:4). They are as cordials to a soul that is ready to faint. The promises are full of virtue.
Are we under the guilt of sin? There is a promise, ‘The Lord merciful and gracious‘ (Exod. 24:6), where God as it were puts on His glorious embroidery, and holds out the golden sceptre, to encourage poor trembling sinners to come to Him. ‘The Lord, merciful.‘ God is more willing to pardon than to punish. Mercy does more multiply in Him than sin in us. Mercy is His nature. The bee naturally gives honey; it stings only when it is provoked. ‘But,’ says the guilty sinner, ‘I cannot deserve mercy.’ Yet He is gracious; He shows mercy, not because we deserve mercy, but because he delights in mercy. But what is that to me? Perhaps my name is not in the pardon. ‘He keeps mercy for thousands‘; the exchequer of mercy is not exhausted. God has treasures lying by, and why should not you come in for a child’s part?
Are we under the defilement of sin? There is a promise working for good. ‘I will heal their backslidings‘ (Hos. 14:4). God will not only bestow mercy, but grace. And He has made a promise of sending His Spirit (Isa. 44:3), which for its sanctifying nature, is in Scripture compared sometimes to water, which cleanses the vessel; sometimes to the fan, which winnows corn, and purifies the air; sometimes to fire, which refines metals. Thus will the Spirit of God cleanse and consecrate the soul, making it partake of the divine nature.
Are we in great trouble? There is a promise that works for our good, ‘I will be with him in trouble‘ (Psalm 91:15). God does not bring His people into troubles, and leave them there. He will stand by them; He will hold their heads and hearts when they are fainting. And there is another promise, ‘He is their strength in the time of trouble‘ (Psalm 37:39). ‘Oh,’ says the soul, ‘I shall faint in the day of trial.’ But God will be the strength of our hearts; He will join His forces with us. Either He will make his hand lighter, or our faith stronger…
Question. How do the promises work for good?
Answer. They are food for faith; and that which strengthens faith works for good. The promises are the milk of faith; faith sucks nourishment from them, as the child from the breast. ‘Jacob feared exceedingly‘ (Gen. 32:7). His spirits were ready to faint; now he goes to the promise, ‘Lord, thou hast said that thou wilt do me good‘ (Gen 32:12). This promise was his food. He got so much strength from this promise that he was able to wrestle with the Lord all night in prayer, and would not let Him go till He had blessed him.
The promises also are springs of joy. There is more in the promises to comfort than in the world to perplex. Ursin (a 16th Century German Reformer) was comforted by that promise: ‘No man shall pluck them out of my Father’s hand‘ (John 10:29). The promises are cordials in a faintint-fit. ‘Unless thy word had been my delights, I had perished in my affliction‘ (Psalm 119:92). The promises are as cork to the net, to bear up the heart from sinking in the deep waters of distress.
Watson, Thomas All Things for Good, Puritan Paperbacks (Carlisle: The Banner of Truth Trust, 2008), 15-7.