We never face any life-situation for which God has not supplied specific promises that give us mercy and grace to help in time of need. The old Puritan Thomas Watson put it very quaintly in a sermon to his little congregation in England on Sunday, August 17, 1662:
Trade much in the promises. The promises are great supports to faith. Faith lives in a promise, as the fish lives in the water. The promises are both comforting and quickening, the very breast of the gospel; as the child by sucking the breasts gets strength, so faith by sucking the breast of a promises gets strength and revives. The promises of God are bladders (flotation devices) to keep us from sinking when we come to the waters of affliction. O! trade much in the promises; there is no condition that you can be in, but you have a promise.J. I. Packer comes round to the same point in his book Knowing God:
In the days when the Bible was universally acknowledged in the churches as “God’s Word written,” it was clearly understood that the promises recorded in Scripture were the proper, God-given basis for all our life of faith, and that the way to strengthen one’s faith was to focus it upon particular promises that spoke to one’s condition.
A promise, of course, is a declaration that one will do something. The promises of God reveal his particular and eternal purposes to which he is unchangeably committed and upon which believers can totally depend. Of course, these promises are made in the context of covenant, and are conditional upon obedience on the part of believers. So, what are the value of God's promises? This question can be answered by considering God Himself.
1. God's promises are irrevocable
God's promises are irrevocable because He is absolutely trustworthy:
"God is not man, that he should lie,
or a son of man, that he should change his mind.
Has he said, and will he not do it?
Or has he spoken, and will he not fulfill it?" (Nu. 23:19)
"...in hope of eternal life, which God, who never lies, promised before the ages began..." (Titus 1:2)
"For when God made a promise to Abraham, since he had no one greater by whom to swear, he swore by himself, saying, “Surely I will bless you and multiply you.” And thus Abraham, having patiently waited, obtained the promise. For people swear by something greater than themselves, and in all their disputes an oath is final for confirmation. So when God desired to show more convincingly to the heirs of the promise the unchangeable character of his purpose, he guaranteed it with an oath, so that by two unchangeable things, in which it is impossible for God to lie, we who have fled for refuge might have strong encouragement to hold fast to the hope set before us." (Heb. 6:13-18)
God's promises are irrevocable because He is unchanging
The LORD has sworn
and will not change his mind,
“You are a priest forever
after the order of Melchizedek.” (Ps 110:4)
“For I the LORD do not change; therefore you, O children of Jacob, are not consumed. From the days of your fathers you have turned aside from my statutes and have not kept them. Return to me, and I will return to you, says the LORD of hosts. But you say, ‘How shall we return?’ (Mal 3:6–7)
"Every good gift and every perfect gift is from above, coming down from the Father of lights with whom there is no variation or shadow due to change. Of his own will he brought us forth by the word of truth, that we should be a kind of firstfruits of his creatures." (Jas 1:17–18)
God's promises are irrevocable because He has the power and will to fulfill His promises
so shall my word be that goes out from my mouth;
it shall not return to me empty,
but it shall accomplish that which I purpose,
and shall succeed in the thing for which I sent it. (Is 55:11)
God's promises are irrevocable because He is faithful in keeping all His promises
"Not one word of all the good promises that the LORD had made to the house of Israel had failed; all came to pass." (Josh 21:45)
“And now I am about to go the way of all the earth, and you know in your hearts and souls, all of you, that not one word has failed of all the good things that the LORD your God promised concerning you. All have come to pass for you; not one of them has failed. 15 But just as all the good things that the LORD your God promised concerning you have been fulfilled for you, so the LORD will bring upon you all the evil things, until he has destroyed you from off this good land that the LORD your God has given you, 16 if you transgress the covenant of the LORD your God, which he commanded you, and go and serve other gods and bow down to them. Then the anger of the LORD will be kindled against you, and you shall perish quickly from off the good land that he has given to you.” (Josh. 23:14–16)
"Blessed be the LORD who has given rest to his people Israel, according to all that he promised. Not one word has failed of all his good promise, which he spoke by Moses his servant." (1 Kings 8:56)
Your kingdom is an everlasting kingdom,
and your dominion endures throughout all generations.
[The LORD is faithful in all his words
and kind in all his works.] (Ps 145:13)
"Let us hold fast the confession of our hope without wavering, for he who promised is faithful." (Heb 10:23)
