This can be a hairy discussion, because it seems there is no way to counteract the "How can God be a loving God and send people to hell?" question. First, remember that this is designed to be a stumper. Most of the time, the doubter is just trying to dodge the issue. I'll try to take a bit of a different tack and see if this makes more sense.
God created man with a free will so he can express his love for God voluntarily. God knows that love must be volitional in order to be true love. Free will cannot be classified as an evil thing, so when God created man He created him in the most loving way possible: perfect, but with free will.
Because man chose to disobey God, the situation changed. We are now not naturally attracted to God's ways, but to ways of rebellion. Because we still possess free will, we have the capability to choose whether we wish to follow God or our own ways. If God were to force us to follow Him, He would not be loving in His actions toward us, and we wouldn't be showing true love to Him.
The other thing we must realize we have received from God is an eternal existence. God wanted us to be with Him forever. He endowed us with spirits that will live forever in some kind of state. In this way we can truly have fellowship with God, for He exists outside of time, and He desires us to relate to Him more intimately than is possible with our limited physical existence.
Once we understand this groundwork, the problem becomes much easier. The Bible says "Every good thing bestowed and every perfect gift is from above, coming down from the Father of lights (James 1:17)." If God is the author all that is good, and someone chooses to live a life separate from Him, they have chosen to separate themselves from the provider of all that is good. In this world that is not always an observable condition, for God has extended a blessing for all based upon His promises and His longsuffering (Matt 5:45). However, when you leave this life behind and you've chosen to separate yourself from God, He will not violate your free will either. The only difference is that you are now going to eternally exist in that chosen state. If you choose to be separate from everything that is good, then what will you have left? What kind of options are open to you if any good thing isn't one of them?
Man chooses to suffer in eternal torment because he chooses to reject God and all His goodness. If you have nothing that is good (no rest, no comfort, no peace) then eternal torment is your only option. God allows us to taste of both in this life so we can make an informed decision about where we wish to spend the next life. It is unfair to ask how God can send people to hell when He's done all He can to stop them from going there! He sent His only Son, Jesus, to die in our place, to suffer instead of us, so we can have a gift of eternal life without having to work for it. He has given us His written word and His church to point the way (although many times imperfectly in regards to the latter.) If God is the author of all good and people have the free will to follow Him or separate from Him, then it must follow that people will suffer if they don't choose to follow God. In this way it is not a "punishment", but the only option left to God who cannot destroy your sovereign will.
I hope this will give you a different perspective on the argument. If I've confused anything, please tell me (I know that I covered a lot of different and complicated points very briefly).
