Kreeft devotes a long chapter to hell in his book "Handbook of Christian Apologetics". He says he does so because it is the weakest link in Christian doctrine in the sense that it is, of all doctrines, "perhaps the most difficult to defend, the most burdensome to believe and the first to be abandoned." We can hope that hell is empty but cannot believe it doesn't exist. (And I don't think any orthodox Christian really refutes that.) Kreeft thinks of it as a way of upholding God's love since they stand or fall together:
If there is no reason for believing in the detested doctrine of hell, there is also no reason to believe in the most beloved doctrine in Christianity: that God is love. The beloved doctrine is the reason critics most frequently give for disbelieving the detested doctrine; yet the two stand on exactly the same foundation.
Why do we believe that God is love? Not by observation of nature, any more than by philosophical reasoning; "nature red in tooth and claw" does not manifest love.
Not by science. No experiment ever verified divine love, or measured or weighed it or even observed it.
Not by conscience, for conscience is "hard as nails." Conscience tells us what is right and wrong and tells us we are absolutely obliged to do right and not wrong, but it does not tell us we are forgiven...
There is one and only one reason anyone ever came to the idea that God is love, mercy, and forgiveness - and only one good proof that this idea is true. That reason is the character of God revealed in the Bible, culiminating in Jesus Christ. The exact same authority which is our only authority for believing God is love also assures us that there is a hell.