The Pineal gland is called the Third Eye because of the reticle receptor rods that are similiar to those found in the eye. IT DETECTS LIGHT.
The pineal gland's primary purpose is to regulate the the body's cicardian rythm & produce melatonin to induce sleep.
Having the pineal gland removed does happen; mostly due to pineal gland cysts.
The people whose pineal gland has been removed CONTINUE to function normally, the biggest impact of pineal gland removal is sleep induction, which is usually treated with melatonin. THIS INCLUDES CHRISTIANS.