Some religions call their normal meetinghouses “temples”. For Mormons, temples are quite different than the church buildings we meet in each Sunday. At the church we have Sunday School, learn about the gospel, have opportunities to serve in various “callings” (like being the librarian or a Sunday School teacher), and most importantly, take the sacrament (bread and water representing the body and blood of Christ) in order to renew the promises we make when we’re baptized.
Just as baptism is an ordinance by which a person becomes a member of the LDS Church, receives forgiveness of his sins, and pledges to live a Christ-like life, there are other ordinances performed in the temple, and only in the temple. They are called washing and anointing, the endowment, and temple marriage, also known as eternal marriage or “sealing”, that is you and your spouse are “sealed” together for eternity. As far as I know, the LDS Church is the only church that claims that our marriages last beyond death, and that families can be together forever, but that’s another topic.
In addition, we perform ordinances for the dead. No, we don’t dig up dead people and baptize their bodies. Live people, members of the LDS Church who are worthy, are baptized in place of the dead. For some reason I don’t completely understand, ordinances like baptism and eternal marriage can’t be performed outside of a temporal existence like we live in on earth. They have to be done here. But what about our relatives and ancestors, loved ones, who never had a chance to know the gospel of Jesus Christ? Some religions say they go straight to hell, because the Bible says you have to be baptized or you’re damned. We believe that’s true, but that if you didn’t have a chance to learn about the gospel here, you can learn about it after you die, and you also have the opportunity to accept baptism (done here on earth, by someone else on your behalf). This only seems fair, since most of the people who have ever lived on this earth never even heard the name Jesus Christ, let alone had the chance to learn more.
For us, the ability to perform ordinances on behalf of our loved ones who have passed on is evidence of the fairness and love of God, that he provides means by which all his children can be saved. The only other way would be for him to force everyone to be baptized, or to have angels flying around to make sure every single person had a chance to learn about the gospel, and of course that wouldn’t really be a choice and therefore not much different than outright force, and we believe God will force no man to heaven.
So what’s secret about the temples? What have I left out? Nothing but the details which, frankly, are not that interesting. If you knew everything in exact detail, you’d say “What, that’s it?” So why don’t we talk about the details of what goes on in the temple? It’s not so much about keeping secrets, but everything to do with keeping things sacred. First of all, we don’t want to expose something that is so special and sacred to us to public ridicule. Second, I’ve found in my own life that when you take something out of the temple into the world, you tend to bring things from the world into the temple. For example, in the endowment ceremony we watch a film about the creation of the world, Adam and Eve, etc. Since we go to the temple frequently, most Mormons have much of this film memorized. Well, I’m the kind of guy who likes to quote things in ordinary conversation, and once or twice I’ve found myself in a humorous situation and a line from the temple movie has popped into my head and before I could catch myself I said it. Now, as far as I know there’s not much in the temple movie that we’re not supposed to share outside the temple–most of it is in the Bible or other scriptures, but the thing is that the next time I went to the temple and watched the movie, when the movie got to that part I had quoted outside the temple, I suddenly found myself thinking of the humorous situation, rather than about what I was doing in the temple.
Now, there are parts of the temple ceremonies that we are ordered to keep secret. Again, it’s not that they’re scandalous, or even interesting (seriously, you would be quite unimpressed), but they are special, sacred, and I suppose God has his own reasons I don’t even know about for wanting us to keep them secret.
Oh, one other thing–not all Mormons can go to the temple. Not only do you have to be a Mormon, but you have to be worthy and of appropriate age. Worthiness is determined through interviews with church leaders and through compliance with certain commandments, such as the law of tithing.
As for people who say “God and Jesus didn’t keep any secrets!” well come now, sure they did. The Bible is full of references to things we’ve never been told about, and examples of reserved access. Not everyone had access to the temple the children of Israel carried in the wilderness. And what was it that was written on the stone tablets Moses broke? Why were only certain people allowed to carry the Ark of the Covenant? Why does God say only married people should engage in sexual relations? If you look through the Bible you’ll find hundreds of instances of such things, so there’s certainly ample precedent.