I will begin by asking, what is our purpose here on earth?
Our purpose on earth is to be tested to see if we will obey God in all things. Simply put our purpose is to be given options of right and wrong and to choose the one which is right. We prepare for a math test by studying, attending lectures, taking notes, and do those things that would help us understand the topic more thoroughly. We do these things so that on the day of the examination we are ready to be tested. Similarly, we prepared in the preexistence to take this mortal test we are now in the process of taking, but unlike the math test there is a veil separating us from most of the knowledge we once had. Why is there a veil at all? When you take a math test you don't forget everything you studied for on the day of the examination, so why must there be one for this test?
This vail seems to be causing so many problems. Take Saul for example, he was a great persecutor of the church, but when Jesus confronted him and made clear to him that what he was doing was wrong, Saul then chose to do right and became a member of the true church. So why would God have a veil, if in many cases people chose to do bad because they cannot see which choice is good and which choice is bad? If there were no veil, then we could clearly see which choices were bad and which choices were good, and those who enjoy evil will chose evil and those who enjoy good would choose good, and the test would be very straightforward. The reason goes back to the purpose of mortal life.
This test must not only be a test of choice but a test of something of even more importance, a test of faith. So why is faith so important that it is worth the price of so many people unknowingly choosing evil? The answer to this that all things are created through faith. This is a very powerful statement. Every particle in the Universe ever acted upon by an intelligent being, was done through the power of faith. At the very least, you must have faith that what you are perceiving is real. Every miracle ever performed was done through the power of faith – "by their faith they were healed.” Once in the celestial kingdom we will be able to create worlds of our own according to our faith.
Another insight is that Satan, the worker of darkness, did not reject God’s plan because he could not chose good when the choice was placed before him, for Lucifer was one of God’s elect. Satin rejected God's plan because he did not have faith that God would decide the best place for his children, and so he created a plan of his own. One third of the host of heaven rejected God's plan because they lacked faith also. Instead settling for a plan that would force all to do good thereby eliminating the need for faith.