No, it has nothing to do with being religious or reading the Bible. It's actually another name for a ganglion cyst (also known as a bible cyst).
I learned about it when a little bump - like a mosquito bite - on my thumb (it rhymes!) began to grow bigger and bigger until it looked like this...
When orthopaedic surgeon saw it he immediately diagnosed that it's a ganglion cyst. Apparently it's a common problem and he was surprised that no one I know has ever suffered from it. Even the nurses could diagnose the problem when they saw it so it's confirmed that it's pretty common after all.
He said I don't have to do anything to it but recommended surgery to remove the cyst, in case it bursts through the skin that is stretched too thin and infection sets in. What do you expect him to say anyway? So I had that pesky little thing removed on 26 January.
So why is a ganglion cyst also known as a "Bible Bump"? According to Wikipedia,
The traditional method of treating a ganglion cyst was to strike the lump with a large heavy book, causing the cyst to rupture and drain into the surrounding tissues. An urban legend states that since even the poorest households often possessed a Bible (referring to the large family Bibles), this was commonly used, which led to the nicknaming of ganglion cysts as "Jillian's lump", "Bible Bumps" or "Gideon's Disease." This type of treatment is not recommended by some doctors as it can damage the area around the cyst and the cyst may come back anyway.