They take a vow of silence or their throat will be cut "from ear to ear". I worked with a few masons, they don't talk. At all.
It's an old builder's guild, they devised secret handshakes to identify themselves to each other - protecting trade secrets. They built the amazing cathedrals all over Europe, involving sacred geometry. Somehow it became more than that. They are possibly connected with the Knights Templar.
The original story has to do with King Solomon's master builder, who was murdered. They have rituals reenacting his death, among others.
I guess it's a kind of esoteric school, a secret society maintaining knowledge from ancient times. I think the story of most of them is that man is asleep, and only with proper knowledge and great effort can he hope to awaken his inner potential. As opposed to the notion that a god is going to fly out of the sky and magically save everyone. They do believe in a higher power, if fact one of the requirements is that you believe in one. Any one.
If they actually have any secrets, I doubt the average mason knows anything.. There are 33 1/3 degrees of masons. The higher ones might know more. It seems to have become more of a social thing, a club for married men to get out of the house. Of course this is all speculation on my part.