To fully appreciate this post, you really need to have read the one just prior (or "below it," in the world of blogs). That said, I'm jumping in.
Several years ago, I heard Dr. Scott Hahn speculate on the fire of hell; and while this isn't what you'd call de fide doctrine, I think many people might benefit from his thoughts. Hahn branched off from what we've already looked at concerning the "fire of purgatory," that it is a transformative encounter with God Himself (Hebrews 12:29, 1 Cor.3:12-15) - the touch of God burning away whatever sin and imperfection keeps us from full participation in His Divine Life. We ourselves are set aflame with this Divine Life; we dwell in the All Consuming Fire, and He dwells in us! Hahn asks if the Fire of Hell could be the same Fire, God - but as He is experienced by a person who refuses Him entry, refuses to be taken up into Divine Life? Keeping God only at the "surface" of their being, they experience Him as "Fire," but refuse the transformative nature of His embrace.
You see, each of us, at every moment, are held in existence by nothing but God's will. That's the corollary truth to having been called into existence from nothing; if we ever ceased to be part of God's will, we would simply unravel. (Wow - that makes sitting on the couch and watching the tube seem pretty spiritual - never mind something as glorious as Bridget cramming that whole White Castle into her mouth). Every being has to be held in existence by Him - there can't be a being who is completely free of His "touch," not even the devil himself. But for one who refuses to be in relationship with Him, this touch would be agonizing. It's like the child, absolutely starving, who stubbornly refuses every bite of food his mother puts before him. He screams and protests, "It's not the food I want," refusing his mother's attempts to explain that it's what his constitution needs. Unwilling to violate her child, she won't shove her fist down his throat and deposit the food in his gullet. Her love for him forces her to let him be, to writhe and protest - becoming ever more angered by her looks of concern.
No one "goes" to hell by accident. It's a choice; a stubborn refusal to accept our place in God's Family. Instead of living within the parameters our Father established for us - established because He created us, and knows what we need far better than we do - we dig in our heels and choose what is incompatible with Divine Life. St. Paul gives a list of such behaviors, 1 Corinthians 6:9. If we choose these over God, and refuse to reorient ourselves, God will not force us to receive Him. He respects our freedom so much that He allows us to keep Him at bay, to create our own experience of hell.