Consider some of the word pictures of God’s wrath in the New Testament. And as you consider them remember the folly of saying, “But aren’t those just symbols? Isn’t fire and brimstone just a symbol?” I say beware of that, because it does not serve your purpose. Suppose fire is a symbol. Do people use symbols of horror because the reality is less horrible or more horrible than the symbols? I don’t know of anyone who uses symbolic language for horrible realities when literal language would make it sound more horrible.
People grasp for symbols of horror (or beauty) because the reality they are trying to describe is worse (or better) than they can put into words. If I say, “My wife is the diamond of my life,” I don’t want you to say, “Oh, he used a symbol of something valuable; it’s only a symbol. So his wife must not be as valuable as a diamond.” No. I used the symbol of the most valuable jewel I could think of because my wife is far more precious than jewels. Honest symbols are not used because they go beyond reality, but because reality goes beyond words.
So when the Bible speaks of hell-fire, woe to us if we say, “It’s only a symbol.” If it is a symbol at all, it means the reality is worse than fire, not better. The word “fire” is used not to make the easy sound terrible, but to make the exceedingly terrible sound something like what it really is.
– John Piper