The prophet Isaiah wrote about the coming kingdom and the Messiah who would rule in that kingdom. His message came from God and not some guess about a future event (2 Peter 1:20, 21). The prophets of the Old Testament inquired (asked about) and searched diligently concerning the grace that would be revealed (1 Peter 1:10). They could write about the suffering of Jesus and wondered what it all meant (verse 11). Since no prophecy of the Scriptures is privately interpreted, one must be able to read and understand what the prophets meant (2 Peter 1:20).
Faith is based on evidence derived from the Word of God (Romans 10:17). As one properly understands verse 17 what is implied is that understanding is a part of faith. The power of the gospel to save lost men rests in the fact that men can come to believe (Romans 1:16). The belief there is about understanding what one has been taught. Jesus directed the apostles back to the Old Testament before He ascended back to the Father. Jesus declared that all things had to be fulfilled which were written about Him in the law of Moses, the prophets and the Psalms (Luke 24:44). Faith requires an understanding of the Word of God. If part of that Word concerns itself with prophecy, then if we are to come to faith we must be able to understand the prophecies.
There are some things that are hidden by God and no man can know them (Deuteronomy 29:29). On the other hand, things that are revealed can be known. Were prophecies revealed, and if so, can they not be understood? If one does not apply effort, then not only prophecy but any portion of Scripture cannot be understood. God is not the author of confusion (1 Corinthians 14:33). The confusion arises when men who are unlearned and unstable wrestled the Scriptures to their own destruction (2 Peter 3:16). If a prophecy is revealed it can then be taught in order to bring about faith in the heart of the person who hears and accepts the prophecy (Acts 17:11).
If one reads, for example, that the Messiah would be bruised for our iniquities, then who is the Messiah (Isaiah 53:5)? Is there more than one Man who died for the sins of mankind and, therefore, satisfied the justice of God (Isaiah 53:11)? I know of no claims by any person who says that they are dying for the sins of man. The prophecy of Isaiah 53 shows us the nature of the problem. In Acts 8, the eunuch asked, “…of himself, or of some other man…” (Acts 8:34). The eunuch was an intelligent man but he could not understand what the prophet Isaiah (chapter 53) was talking about. Philip preached unto him Jesus and then he understood. What if man cannot understand prophecy? Where would faith come from?
In Isaiah 30, the prophet states about the people of God, that they would “weep no more.” (verse 19). Can such a prophecy be understood? Once more, if one is willing to make the effort, then, yes, this prophecy can be understood. The verse speaks about Zion (southern part of Jerusalem) and Jerusalem (Isaiah 2:2,3). The returning of the Jews from Babylonian captivity was before the “last days.” This, then, refers to something else. Jesus, beginning in Matthew 5, tells us the kind of people who would occupy his kingdom. One of the descriptions is found in Matthew 5:4. Those who would mourn (crying for sins) would be comforted. The passage in Isaiah 30:19 says that the people of God would weep no more. It is conveyed to us, then, that Christians will always have reasons to be weeping for the trials they would be going through (I Peter 1:6). The mourning of Matthew 5:4 is a mourning for sin. It is a mourning that would be lost when a person obeyed Christ and became a Christian. They, by obedience to Christ, would be comforted by Him.
Some prophecies require greater effort but it does not mean we cannot understand what God has revealed. Searching the Scriptures and accepting what one has heard can certainly lead to faith. The person who chooses ignorance, because they choose to not make an effort, will place God in the position of being the author of confusion. We can and should know what the Bible shows us.