The following is quoted from Gordon B. Hinckley, who was speaking at a Conference in April 1973. He was speaking of a young naval officer that he once met, one who had recently converted to Christianity.

He was introduced to me just before he was to return to his native land. I said, "Your people are not Christians. You come from a land where Christians have had a difficult time. What will happen when you return home a Christian?" 
His face clouded, and he replied, "My family will be disappointed. I suppose they will cast me out. They will regard me as dead. As for my future and my career, I assume that all opportunity will be foreclosed against me." 
I asked, "Are you willing to pay so great a price for the gospel?" 
His dark eyes, moistened by tears, shone from his handsome brown face as he answered, "It's true, isn't it?" 
Ashamed at having asked the question, I responded, "Yes, it's true." 
To which he replied, "Then what else matters?"

Often the world criticizes the principles and commandments found in religion, stating that adherence to a strict moral code is outmoded, and that the gospel needs to get with the times. They focus primarily on the behaviors that religion calls for, but do not ask whether those behaviors are based upon true premises.
In my experience, the observances followed by most world religions are remarkably consistent with the claims of that gospel. For example, Christianity teaches that each person is composed of an immortal spirit paired with a mortal body. It teaches that God created the first man and woman, and authored the institution of marriage between them. It teaches that we come to this earth life in order to gain a body, to learn to follow God’s will, all so that our perfected self can live with Him after the resurrection.
Now if all of these claims are true, then obviously there is an awesome responsibility related to birth, life, and the union we call marriage. If these premises are true, then it matters greatly how we deal with these subjects, and it is only logical that there would be laws to govern them.
If these claims are true, then doesn’t it make sense for there to be laws of chastity and sexual purity? Doesn’t it make sense for there to be safeguards that protect the sacred procreative power which binds an eternal soul to a mortal body? Doesn’t it make sense for marriage, and the definition of it, to be under the purview of the God who invented it? Doesn’t it make sense to master one’s appetites as necessary to pursue the true purpose of life?
If these claims are true, then what else matters? If these claims are true, then any argument that God’s laws are “outmoded” become hollow. If these claims are true, then these laws are simply the natural, logical extension of what is right.
Thus the only meaningful question is the one asked by that young sailor. Is it true, or not?