Thanks for thinking about such topics! I was very intrigued when I first heard of this idea, and I've grown to accept it over the years. My pastor has written a fantastic article on why he believes in universalism, and it has a bunch of verses supporting this said belief:
http://www.tsdowntown.com/images/essays/all_things_new_and_a_place_we_call_hell.pdf
One thing that I find interesting, though, is that when I read the bible with this belief, I've found that many verses seem to be consistent with this idea. It just requires changing our understanding of a few things:
- God's "judgment" is not eternal torture, but mercy. It's a fire that may burn "like hell" but will cleanse you and make you whole. It's a judgment of the old man that turns him into the new man.
- Hell may be temporal, and so it may come to an end. Unbeliever's may be tortured for a time (just as we on Earth are tortured for a time) but God's love will prevail in the end.
Another argument that's meant alot to me (but doesn't really have a basis in scripture) is that I believe God to be infinitely more loving than I am. Therefore, if I feel that it is cruel for a person to be tortured forever, wouldn't God also? And, being that he is all-powerful, wouldn't he choose to save that person?
EDIT:
Here's just a few verses that are discussed in detail in the referenced document:
God desires all to be saved: 1 Tim. 2:1-6, 2 Peter 3:8-10
Isaiah 45:22-23
John 12:30-32 (particularly 32)
Romans 5:15-19: "For if the many died by the trespass of the one man, how much more did God’s grace and the gift that came by the grace of the one man, Jesus Christ, overflow to the many!" To me, this states that God's grace overflows to the many in the same way that the trespass of Adam was given to many; in other words, every human being.
Romans 11:32
1 Corinthians 15:22
Colossians 1:15-20: Look at all the parallel "all"s. How could we possibly say that the "all" in 20 is different from the "all" in 15?
Revelations 21:5