Belief in God presupposes that God, being perfect, possesses truths that are sufficiently advanced that they would be repulsive to the natural man. Whereas non-believers might be tempted to only accept truths that are somehow tethered to their present position, believers in God ought to assume that even their most prized positions have the potential of being supplanted by higher truths, even if they cannot presently anticipate exactly what these might be.
The path to truth will undoubtedly intersect difficult experiences. The gospel does not remove these. If anything, more trials occur in a life of a believer than a non-believer. However, the gospel provides a framework where one can remain in a state of happiness and internal comfort in spite of great external turmoil. Those who know God can understand the truth and beautiful reality of Jesus’ promise that his teachings make burdens light.
Can you endure the endless trials that are required to refine you into the likeness of God? To do it, you need promises—assurances from God that what you are going through is for your good. Do promises exist for those merely trying to be good?
God provides promises to those who keep his commandments. For example, consider this promise given to a man who gave his all to live in accordance with new truth God showed him:
And I will also be your light in the wilderness; and I will prepare the way before you, if it so be that ye shall keep my commandments; wherefore, inasmuch as ye shall keep my commandments ye shall be led towards the promised land; and ye shall know that it is by me that ye are led. (1 Nephi 17:13)
Those who follow the Lord will always be good, but those who try to be good may not succeed in their objective: “And see that ye have faith, hope, and charity, and then ye will always abound in good works.” (Alma 7:24) Sanctification, or becoming more perfect, will always happen as an individual yields their heart to God:
Nevertheless they did fast and pray oft, and did wax stronger and stronger in their humility, and firmer and firmer in the faith of Christ, unto the filling their souls with joy and consolation, yea, even to the purifying and the sanctification of their hearts, which sanctification cometh because of their yielding their hearts unto God. (Helaman 3:35)
Peace within and peace without is completely possible. And a relationship with God makes it enduring no matter what may come, whereas an unbeliever may find themselves consistently or occasionally encountering situations that rob them of their peace.