One of my favourite shows to watch as a young lad was a show called Horrible Histories. This show, presented by a puppet rat (whose name escapes me) intended to give true historical facts to kids in a funny way. One of the strangest things I remember from this show was the Celtic army's attitude to armor. They didn't wear any. In fact, the Celts would apparently fight naked, believing if the gods thought it was their day to die, no amount of armor would save them.
Just imagine that silly scenario. Hordes of Viking berserkers charging at these silly little naked men. Who's coming out of that battle on top? But one thing no army has ever been foolish enough to do is go into battle without a weapon.
It is no surprise, then, that the item the Bible most identifies itself with is the sword. By far the most important item in a real war, the primary weapon is used for both attack and for defence. Go into battle without armor, you're in trouble, but go into battle without a weapon, you are doomed. In much the same way, you cannot expect to cruise through life without the Bible. Neglecting the Bible leaves you open to constant spiritual attack, and with no way to defend yourself, you will lose.