God has proven His faithfulness in the past, spanning two millennia. He formed Israel, grew her, and protected her. She was the apple of His eye. To do so, God often did what no one but He could do. He acted in a way that connected the past with the present, the present with the future, and the future with the past. God showed that He was working all things together for His glory.
After the contents of most of the first half of Isaiah, hearing and reading God's destruction of Israel's enemies, especially Assyria, Israel could find satisfaction that God had indeed done what she desired for her protection. She could feel safe. But at the end of the first half of the book, God introduces a new problem for Israel---Babylon. The second half of Isaiah answers the question posed by the presentation of this new enemy and her thoughts of a precarious future.
The Evidence of God
To comfort the hearts of His people, so that they would wait on Him, God presented evidence of His care and concern to them. This evidence would indicate that God was working during these periods they thought were silent. Sometimes men want more than what God has to offer, even though God gives men far more than what they deserve. God wants men to take Him into serious consideration in His credentials as God, even to make comparison with other potential gods that might be deserving of equal credit with Him. In Isaiah 41:17-20 God describes what He does that sets Him apart from all others:
17 When the poor and needy seek water, and there is none, and their tongue faileth for thirst, I the LORD will hear them, I the God of Israel will not forsake them. 18 I will open rivers in high places, and fountains in the midst of the valleys: I will make the wilderness a pool of water, and the dry land springs of water. 19 I will plant in the wilderness the cedar, the shittah tree, and the myrtle, and the oil tree; I will set in the desert the fir tree, and the pine, and the box tree together: 20 That they may see, and know, and consider, and understand together, that the hand of the LORD hath done this, and the Holy One of Israel hath created it.
You may have skipped the text itself to get here. Go back and read it. The Lord does things about the needs of men. He alone can break into man's box of space and time and rescue, because He alone stands non-contingent from the frailty and futility of an unredeemed universe. But God does invade this dimension to save. In doing so, He wants me to see His goodness and uniqueness, that there is none like Him and that He did create earth and men. This obviously wasn't enough for many, if not most. They needed God to do more. God out of His mercy puts Himself to other possible gods in a contest, beginning in v. 21:
21 Produce your cause, saith the LORD; bring forth your strong reasons, saith the King of Jacob. 22 Let them bring them forth, and shew us what shall happen: let them shew the former things, what they be, that we may consider them, and know the latter end of them; or declare us things for to come. 23 Shew the things that are to come hereafter, that we may know that ye are gods: yea, do good, or do evil, that we may be dismayed, and behold it together.
Again, make sure you read the verses. God asks for evidence and if He gets it, He will know that they are gods. He would give them credit if they could produce God-like proof. The evidence He asks for is prophetic. He wants these to show what will happen and how the things in the past relate to those things that will take place in the future. He wants that from them, because this is something God can do. Surely if one is god, it could do the same. Of course, these predictions would be about things that a god itself would be able to then follow through and make happen. God asks for something good or evil (in essence, nasty), that will blow everyone away, something that no one could miss. God not only predicts, but predicts events that are beyond human comprehension. He can do those types of acts. The assumption in v. 24 is that they could not produce such evidence:
Behold, ye are of nothing, and your work of nought: an abomination is he that chooseth you.
They couldn't fulfill such criteria and win this contest, because they were nothing. They were not gods at all. Because of that, God says that those who choose them are an abomination. However, God could produce evidence, and at the end of chapter 41, beginning in v. 25, He makes a prophecy Himself to show that He had that ability. You can read the prophecy there to the end of the chapter.
God's Words Are Evidence
So what God is saying is that He backs up what He says by fulfilling what He says that He will do. He can do that because He is God. That is a basis for believing in Him. If He says He will do something, He will do it. He providentially works. We look for Him working, even if He hasn't announced how it is He is accomplishing what He promised.
Now sometimes God will say He is doing something or that He will do something and the evidence is not quite so evident. God still wants to be believed. Why? Because His Words themselves are evidence. If God says it, it counts as though it has already happened. This is the way that we place faith in Him. It doesn't please God when we don't believe what He said. We can see in several places in scripture that He is angered by those who need signs or some other tangible means to indicate the reality of what He has promised.
The history of God's people is a chronicle that is peppered with men who acted on God's promises and believed based upon Who He said He was and upon what He said He would do. He is pleased by that faith. He is not pleased when men require something more than that. This is not how He has chosen to operate, that is, where men keep requiring external evidence, over and above God's promises.
Many of the truths that God expects us to believe, we have no means of believing except what He said. I've never seen resurrection. I've never seen ascension. I don't know what God's justification looks like. I don't have the original manuscripts as a basis for checking on the copies to see if He actually did preserve the Words like He said He would.
Going door-to-door last week, I had a Roman Catholic who told me that he would take my King James Version and throw it in the fire. It wasn't the Bible. Why? It didn't have all of the books. It should include the apocrypha. He believed the Douay-Rheims Version, which was translated from the Latin Vulgate, was the only acceptable Bible. So why only sixty-six books? Because those are what the church handed down to us. Believers accepted only those sixty-six, no more, no less, even though God didn't tell us what their names were. They received those books, therefore, they were His Words. God's people receive His Words. That's how they come to a knowledge of which ones are God's.
God said He would guide His children into all truth. We assume that they would have accepted and then made copies of the apocrypha if those were legitimate books of scripture. Instead we think that those are imposters based upon the testimony of believers. Those books, besides containing error, maybe not enough to reject the gospel or Christ (but error nonetheless), also were not recognized by God's people as the books of Scripture. Only sixty-six were recognized as such.
God Fulfills His Promises
The Holy Spirit works through righteous men for agreement upon what His Words are. They unify around truth. They believe He has preserved every Word. They believe that all the Words are accessible so that none that are not accessible could be His Words. They know of copying errors. They know of variants between manuscripts. But they believe that God's promises override those issues---that what mistake may be made in one copy is corrected by another. This was established and settled in the sixteenth century. This is what men of God believed.
During the nineteenth century men left this standard based upon scripture. As part of the new enlightenment thinking, they were convinced that those promises weren't good enough. The text received by the churches, led by the Spirit of God, based upon the promises of God, needed to be exposed to the correction of man's reasoning. What God said, connecting the past with the present and the present with the future, that wasn't good enough. And so rather than bow to the Bible as found in those promises, men submitted the Bible their own reasoning. Responding to promises was not good enough any more.
Are God's promises evidence? Can we count on His providential working in history? When Israel couldn't see what God was doing, she went out looking for her own solutions to give herself her own assurance. It was during those times especially that God wanted her to understand that He was working, accomplishing His will just as He said. And especially as it applies to His Holy Word, we should not question it or determine it based on man's reasoning bereft of scriptural doctrine. We should trust that God would do what He said He would do. He did it in the past, so He can do it in the future too.
Does God do what He says He will do? Yes He does. And the just shall live by faith.