The key is that as believers, we must look at what is "left out" as intentional as what is put in. Because the Lord has ordained each word, we know that He has a purpose for those things He has not included. Take for example Paul's "thorn in the flesh" referenced in 2 Corinthians. In this passage, Paul does not specify what the issue is. He tells us just that it is something that weakens him, something he has prayed to asked God to remove, and something God has decided will remain. This issue Paul has is something that God has chosen to use to teach Paul about the sufficiency of His grace. And we will never know what "it" is on this side of heaven.
Sure, we can speculate, and I am sure that we do. I imagine that there may be theologians who think they know exactly to what Paul is referring. But the fact of the matter is that they cannot know, and that is because God does not want them to. If He wanted us to know, He would have told us, and that is the whole point. There are things that God doesn't tell us, and He has a reason why.
In the case of Paul's thorn in the flesh, there could be many reasons why God left that detail out. What I am guessing is that it is better for the believers who would follow and read Paul's account not to know--not to have a specific thought or idea in mind about what Paul suffered with so that the principle and truth of the matter would stand out more clearly. What is that principle? That in my weakness, Christ is strong and His grace is sufficient for me, no matter what my weakness is.
Let's say Paul actually stated what his "thorn" was. Maybe it was a physical challenge, or even a temptation in the flesh that he wrestled with. The point is that if we knew what that weakness was for him, then in our finite minds, we would not be able to apply the broader truth. "Sure, God's grace is sufficient for Paul's problem, but mine is different, mine is worse. I don't know if God will cover me with grace like He covered Paul." You don't imagine that type of thinking is possible? Of course it is. We do it already, even given the full knowledge of the truth of God. And God knows that.
God knows us. He knows the way we are, and He loves us...with all of our weaknesses and "issues," His grace and His love covers us. And that is why He left some things out. He knows what we need to know and what we don't. His truth is perfect and complete, including all the things He didn't say.
But he said to me, “My grace is sufficient for you, for my power is made perfect in weakness.” Therefore I will boast all the more gladly about my weaknesses, so that Christ’s power may rest on me. That is why, for Christ’s sake, I delight in weaknesses, in insults, in hardships, in persecutions, in difficulties. For when I am weak, then I am strong.
2 Corinthians 12:9-10
2 Corinthians 12:9-10