Telling the truth is easy in theory and hard in practice. Doesn’t everyone have something that they don’t really want to tell their parents? Even those of us who don’t have anything huge to hide might get a grade or two that’s embarrassing, or do something that’s not illegal or immoral, but that our parents might not understand. (We’re sure they won’t.)
So maybe we don’t want to tell our parents everything—or our friends. Maybe we’d like to keep some things to ourselves, and that’s perfectly all right. Privacy is a human and teenage right. You don’t need to go home every day and chronicle to your parents exactly what happened and why. (In short, you don’t need to tell your parents about that toilet paper that got stuck to your shoe, but important things like detention, grades, and so forth probably need to come to their attention.)
The Mormon Church (officially The Church of Jesus Christ of Latter-day Saints) puts high importance on honesty. If your grades are embarrassing, it’s one thing to say you don’t want to talk about it, and another to make up new grades. The problem with lies, beyond moral reasons, is that they tend to get found out. Saying you have an A when you have a D might get you out of a lecture now, but when parent-teacher conferences roll around (or when your teacher makes a call home), you’re going to end up with two lectures.
That’s the problem with sin, generally. You may escape punishment for the short-term (if you’re lucky!), but when the consequence comes, it’s a lot worse than it would’ve been otherwise.
When you’re honest, you’re honest with yourself as well as others. Lies can fool more than other people. Self-deception’s always possible. The more you lie to others, the more reality can get a little fuzzy. Juggle too many stories and the stories will start sounding true. No, I really did do that and not that; no, I really did get that when I said I did; no, I’m really not lying.
Mormons know that honesty takes courage. You might have to steel yourself before telling some truths, but it’s worth it.
Stealing is always bad, and by the law of the land, not just in Mormon doctrine—and always dangerous. How many times do you think you can get away with shoplifting before you either get caught or it becomes a really destructive habit? A lot of kids stuff a piece of gum in their pockets once or twice before they know better. You know better. What pair of shoes or candy bar or whatever is worth the risk and the guilt?
Cheating is similar to stealing and lying. Like stealing, like lying, it’s a short-term gain with long-term consequences. You might (might) do well on that test if you look over at someone else’s paper, but you might get caught. And even if you don’t, you can form a habit of looking for ways besides actually learning the material to get a good grade. In the end, grades aren’t going to do you any good if you don’t know anything the class was supposed to teach you. It’s a commonly used example, but, really, what use would be a medical doctor who cheated his way all through school?
Dishonesty is a shortcut that doesn’t actually lead to where it looks like it leads. You feel like you’re gaining, but, in the end, you end up with nothing. You end up exposed for what you’ve let yourself become. And, in the meantime, you’re not even happy. Mormons believe that wickedness never was happiness and never will be.