Dear 100 Hour Board,
What things about the temple can we not talk about those not endowed, or those who are not members? Obviously what the robes or garments look like aren't as secret as I once thought, as the church has made a video about temple related clothing.
To preserve the sanctity of the temple, what are some things we simply say we won't talk about, and which things can we talk about to the un-endowed?
Kirito quotes below that the "phraseology" used in the temple shouldn't be used specifically outside of the temple. This was interesting for me, and felt correct with some feelings I haven't been able to place lately. Recently I haven't had words outside of the temple phrases to express things I learned there, so I used them, but it didn't feel right. Kirito's answer gave me an idea as to why:
If certain things are specifically and only found in God's house, then to take them out of it seems akin to stealing. That could be off, but it feels okay for now.
With that said, He does not leave us without testaments of the truths of the things we learn there. I mean, Genesis and Exodus hold most of the scripts of the endowment video and the initiatory ordinance. And there are themes of the Creation, the Fall, and the Atonement throughout literally everything.
Additionally things can be taught line upon line, and they will be understood according to individual capacity and experience. For example, I remember an EFY lesson where the director took a bunch of 14- to 18-year-olds through a few verses in Genesis 3, and showed us principles of works and grace and the Atonement. He talked about the absurd ineffectiveness of fig leaves in covering nakedness ("Can you imagine if it was windy!?"), and then pointing out what had to happen for coats of skins to be made, which is that blood had to be shed in sacrifice for the wellbeing of Adam and Eve.
And I was like 14! And that was amazing! And it got even more amazing the closer I got to the temple.
Moving forward, look to the scriptures, both ancient and current. Truth is all around if you have the right lens, and the scriptures are key to that.
I found two quotes that might help.
Handbook 2 mentions that "Local leaders make sure that temple phraseology and the sacred ordinances and covenants of the temple are not discussed in specific terms in Church meetings."
The Church pamphlet, "Preparing to Enter the Holy Temple," states, "We do not discuss the temple ordinances outside the temples. . . . They are beautiful. They are sacred. . . . The Lord has every right and authority to direct that matters relating to the temple be kept sacred and confidential. All who are worthy and qualify in every way may enter the temple, there to be introduced to the sacred rites and ordinances."
From these two quotes, I gather that we should not discuss specifics about the temple ordinances outside the temple. With a few exceptions, you won't be breaking covenants if you slip up and mention something. But we keep it to ourselves anyway because of how sacred it is. If you want to share something you've learned, find a way to do it quoting scripture. Or you can quote from the "Preparing to Enter the Holy Temple" pamphlet, which has quite a bit about the temple. But in my opinion, it's hard to go beyond that and maintain a sacred attitude towards the temple ordinances.
Most of all, follow the Spirit. And err on the side of caution with this one.
The above answers are great, and I just want to add that from what I understand, the things we specifically covenant not to share with others are the only things that we aren't supposed to talk about outside the temple. Other than that we're just generally not supposed to talk in detail about the temple or, as Kirito pointed out, use temple-specific wording. But that's just how I've come to understand it.