In Isaiah 55:8-9 we read these familiar words: "For My thoughts are not your thoughts, neither are your ways my ways, declares the Lord. For as the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts." These are amazing verses that offer us comfort. We can go to them in times of hardship, in times of disillusionment and remind ourselves that when we don't know what God is doing, He does; that when we can't see how it will work out, He can. Those are precious truths, anchors that help secure our souls. Those truths are also not the point of these verses.
One of the most important parts of interpreting the Bible is context, i.e., what do the verses above and and the verses below say? If we read these verses by themselves then the above interpretation might seem to be the proper interpretation. However, a careful reading of these verses in context shows us that's not exactly what these verses are referring to. Again, I'm not saying that's not true and I'm not saying we shouldn't apply that truth to our hearts. But I am saying there's more here than just "God knows what He's doing even when I don't." What do the verses immediately before this text say? "Seek the Lord while He may be found; call upon Him while He is near; let the wicked forsake his way, and the unrighteous man his thoughts; let him return to the Lord that He may may have compassion on him, and to our God, for He will abundantly pardon." Nothing in those verses about God having some greater plan for our lives (though He does). And nothing in those verses about God knowing what He's doing even when I don't (but He does). Rather, these verses present a call to seek God and His mercy.
So the point of verses 8-9 isn't that 'God works in mysterious ways, His wonders to perform' (though He does). The point is the greatness of the gospel. In the first two verses of the chapter God says, "Come, everyone who thirsts, come to the waters; and he who has no money, come, buy and eat! Come buy wine and milk without money and without price. Why do you spend your money for that which is not bread, and your labor for that which does not satisfy? Listen diligently to Me, and eat what is good, and delight yourselves in rich food." God here calls us to Himself, to come and buy though we have no money. How is this possible? By grace, through faith, and that not of ourselves. God is calling us to experience the free gift of salvation is available through repentance and faith in the finished work of Jesus. And it's in that context that God says, "My thoughts are not your thoughts." Nothing demonstrates this more clearly than the gospel-who else but God would create such a plan of salvation? Every other religion in the world is based on our works; but God bases His salvation solely on His grace, His mercy, and merits of Jesus' life, death and resurrection.
So must we abandon our hope that God knows what He's doing even when we don't? By no means. Rather, we embrace it even more fully. We look at the sufficiency of the gospel, at the guarantee of its success and of the fruit it produces in the lives of those who are saved and we glory in the greatness of our God. We glory in His brilliance and His preeminence. We look at the gospel and shake our heads in holy amazement at the plan and the God who created it accomplishes it. And we rest in that gospel, worshiping the One whose thoughts are above ours and whose ways are higher than ours.