"...principles and values and ideals that we devoutly hope are true, and have reasonable but not certain grounds for believing to be true." (Testimony of Terryl L. Givens as found from Clean Cut)
This quote highlights what I have come to understand. That faith is a choice. The Lord gives us reasonable grounds for believing in Him and His principles. Yet they are not certain ground. Our life is an exercise of our faith which begins as a desire to believe. As Terryl said, there is also grounds for doubt.
I am reminded of Moroni where he says that I can know of spiritual truth as surely as I can distinguish between the daylight and the dark night. I know this is true for the most important things. The things that cause us to progress or to be damned. I know clearly that I am to be kind to my wife and children. I am to work hard and trust God. I am to be meditative and prayerful. I am to seek truth in the scriptures and from other good sources. I am to listen to the still small voice. I am to seek the Spirit of God and discipline myself to follow it. So I can establish trust between my Father and I. So I can enjoy the delicious joy He brings into my life.
We have reasonable but not certain ground to believe God. Yet He always respects our choice. He will force no man to heaven. The reward is greater than any other thing. It is worth any effort to receive it.