Why is faith in Jesus Christ so important?
Why does God not simply reveal all things to everyone, making faith unnecessary?
Does God intentionally obscure information to pressure a choice between faith and unbelief? If so, why?
Let's start with Alma 41 for answers to these questions.
At the last day we will all be raised, or resurrected, to a state consistent with the desires of our heart while in this life. If "the desires of their hearts were good, that they should also, at the last day, be restored unto that which is good...and if their works are evil they shall be restored unto them for evil...The one raised to happiness according to his desires of happiness, or good according to his desires of good; and the other to evil according to his desires of evil" (v. 3-5)
God already knows our hearts. He knows our inmost desires. We, however, do not know our own hearts. But because of our experiences in mortality, the true desires of our hearts will be revealed by the choices we make and we will come to know who we truly are at the core of our beings. Abinadi speaks to this in Mosiah 16:1 "The time shall come when all shall see the salvation of the Lord; when every nation, kindred, tongue, and people shall see eye to eye and shall confess before God that his judgments are just."
So what does this have to do with faith? Lehi speaks directly to this question in 2 Nephi 2:16, 27 "Wherefore, the Lord God gave unto man that he should act for himself. Wherefore, man could not act for himself save it should be that he was enticed by the one or the other...wherefore, men are free according to the flesh; and all things are given them which are expedient unto man. And they are free to choose liberty and eternal life, through the great Mediator of all men, or to choose captivity and death, according to the captivity and power of the devil."
By not revealing all things to us fully, which would eliminate the need for faith, God provides a context for us to be "enticed by the one or the other" so we can, in truth, choose for ourselves.
So we can answer the questions above clearly:
Yes, God does withhold knowledge, pressuring us to make a choice between choosing righteousness or wickedness based on desire. Because we must make that choice, over and over again throughout life, without all the knowledge of God, our choices become a reflection of our true desires for good or evil, rather than a selfish race for the prize or fear of punishment.
Those who genuinely "hunger and thirst after righteousness" will be led by the promptings of the Holy Ghost, which requires faith, to follow Christ.
The good news is, we get to choose! We are not coerced by God. We have every reason for optimism and hope! If we examine our hearts and consistently push ourselves to choose good and seek God, He will send the Holy Ghost to enlighten our minds, direct our path, and help us grow into truly Christlike beings! Without the need for faith, this simple and beautiful process would not be able to play out.
As I reflect, I feel to exclaim with Lehi "behold, all things have been done in the wisdom of him who knoweth all things." (2 Ne 2:24)