I gave the following brief reply with minor editing. I've also added material that wasn't in the original response in purple:
There are many non-ultimate reasons, and other ultimate reasons.
- Our efforts, diligence and industry in trying to understand the Bible reveals our sincerity and seriousness in knowing about God and His ways. It weeds out those who aren't serious and sincere. Our response to the Bible exposes our character. It also affords room and possibility for rewards for diligence. Raking is easy, but you only get leaves. Digging is hard, but by doing so you can find diamonds and gold. Most people are only willing to rake the Bible. Because of our sinful nature, we are naturally intellectually lazy and immoral and biased in our reading/studying of the Bible. Yet, we are that way willingly, and therefore culpably so.
Prov. 25:2 It is the glory of God to conceal things, but the glory of kings is to search things out.
-A critic might ask, "Why couldn't Jesus and/or the Bible refrain from using idioms and only use pure universal unambiguous propositional prose so that every generation of Bible readers could understand plainly?" It's not clear that human language can be completely free of the use of idioms, emblematic language and other non-propositional like language. See the first section [pages 2-5] of Steve Hays' article here to get my meaning and point:
Why I Believe by Steve Hays
-Often, it's not just/merely the clear propositional aspects of the Bible that inspire faith [which is more than mere belief BTW], but it's often the narrative thrust of the Bible that often does so even more. Non-Christians understand how powerful narrative is in forming/developing morals. That's why Hollywood has been taken over by the most radical non-Christians. Why the woke want to impose their values on both theists and non-theists.
- A completely understandable Revelation this side of death [and of the eschaton, the final Day of Judgment and Final Manifestation of God] wouldn't capture & sustain the continual intrigue and fascination of humans for very long. Even regarding wonderful earthly things, we often take them for granted because they are so common and easily understood. This is why even ordinary human poetry and Shakespeare's works fascinate people who don't fully understand them. The mystery adds to and is part of the enjoyment. The more you dig into the Bible the more gold is found. Many Christians know by experience how studying a Biblical subject can be very enjoyable and awe inspiring.
Take for example the subject of the Messiahship of Jesus. Here's a link to Messianic Jew Arnold Fruchtenbaum's 21 lectures on the Jewish Life of Christ:
More could be said and enumerated regarding non-ultimate reasons. But I'll leave it at that.
The ultimate reason is that in God's sovereignty, He has inspired Scripture to say what it does in order to save the guilty elect and judicially condemn the guilty non-elect.
I'm a Calvinist Protestant, but even high predestinarian Catholic Blaise Pascal wrote in his famous Pensées:
//Willing to appear openly to those who seek him with all their heart, and to be hidden from those who flee from him with all their heart, God so regulates the knowledge of himself that he has given indications of himself which are visible to those who seek him and not to those who do not seek him. There is enough light for those to see who only desire to see, and enough obscurity for those who have a contrary disposition.//
//563 The prophecies, the very miracles and proofs of our religion, are not of such a nature that they can be said to be absolutely convincing. But they are also of such a kind that it cannot be said that it is unreasonable to believe them. Thus there is both evidence and obscurity to enlighten some and confuse others. But the evidence is such that it surpasses, or at least equals, the evidence to the contrary; so that it is not reason which can determine men not to follow it, and thus it can only be lust or malice of heart. And by this means there is sufficient evidence to condemn, and insufficient to convince; so that it appears in those who follow it, that it is grace, and not reason, which makes them follow it; and in those who shun it, that it is lust, not reason, which makes them shun it. //
//577 There is sufficient clearness to enlighten the elect, and sufficient obscurity to humble them. There is sufficient obscurity to blind the reprobate, and sufficient clearness to condemn them, and make them inexcusable.—Saint Augustine, Montaigne, Sébond.//
//574 All things work together for good to the elect, even the obscurities of Scripture; for they honour them because of what is divinely clear. And all things work together for evil to the rest of the world, even what is clear; for they revile such, because of the obscurities which they do not understand.//
//562 It will be one of the confusions of the damned to see that they are condemned by their own reason, by which they claimed to condemn the Christian religion.//
//576 God has made the blindness of this people subservient to the good of the elect.//
My point being that if the Bible were any more clearer OR any more ambiguous in either direction, not all and only all of God's elect might be saved. Though, the doctrine of predestination and the various options available to Christians is an in-house debate in Christianity and shouldn't take a center stage or usurp attention from the main issues. Christians are free to disagree on this topic. Whether one is a Calvinist like myself, or an Arminian, or middle knowledge Molinist, or middle knowledge Congruist, or Augustinian et cetera.
Also, if the Bible were too clear, then God's providential plan for history [or literally HIS-story] would not come to pass. The progress of Redemptive History and of civilization, with all it's ups and downs, are part of God's plan to glorify Himself and prove man's need for God. There are three main views on the Millennium among Christians. All three are within the pale of Christian orthodoxy. Amillennialism, Premillennialism and Postmillennialism. If postmillennialism is true [as I suspect], then one day the world of humanity will eventually be fully evangelized and Christianized such that the majority of humanity will be saved on earth and all aspects of society will be sanctified. That's a process that will take time. A process that will bring greatest glory to God. Just like in superhero movies the origins story with all its struggles and ups and downs to develop character in the protagonist makes the journey all the more glorious. God is like the Mickey to the Rocky of human history. Or the Mr. Miagi to the Karate Kid of human history. Or the Obi Wan Kenobi to the Luke. You also need a Vader to fight the Luke. The wheat must struggle with the tares/weeds [cf. the Parable of the Wheat and Tares in the Bible].
Even if I'm wrong about Postmillennialism and Premillennialism or Amillennialism were true, a Bible that were much clearer wouldn't result in fulfilling either the Premil or Amil position.
Also, God's ways are deeper and higher than our ways. Moreover, God's nature, while truly apprehensible, is nevertheless incomprehensible. We can apprehend God to some degree, but we cannot fully comprehend God exhaustively. The finite cannot contain the infinite.
Rom. 11:33 Oh, the depth of the riches and wisdom and knowledge of God! How unsearchable are his judgments and how inscrutable his ways!
34 "For who has known the mind of the Lord, or who has been his counselor?"
35 "Or who has given a gift to him that he might be repaid?"
36 For from him and through him and to him are all things. To him be glory forever. Amen.
Isa. 55:6 "Seek the LORD while he may be found; call upon him while he is near;
7 let the wicked forsake his way, and the unrighteous man his thoughts; let him return to the LORD, that he may have compassion on him, and to our God, for he will abundantly pardon.
8 For my thoughts are not your thoughts, neither are your ways my ways, declares the LORD.
9 For as the heavens are higher than the earth, so are my ways higher than your ways and my thoughts than your thoughts.
10 "For as the rain and the snow come down from heaven and do not return there but water the earth, making it bring forth and sprout, giving seed to the sower and bread to the eater,
11 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.
