You used several interesting names of characters and places in Edge of Eternity. What do they represent?
Pierasmos is the Greek word for trial, so it connects to the whole trial they went through on the mountain. As you may know, Charis is Greek for grace, and seemed an appropriate name for heaven.
Erebus is an old word sometimes used of hell.
The dog had no symbolic meaning. I put him there to allow Nick to have someone he could be vulnerable with, at ease with, to bring out a kinder side to his personality that wasn't coming out with people because of his defenses.
No, I don't believe in purgatory. Edge of Eternity just has an imaginary world that allowed me to depict invisible spiritual realities in visible ways. The trees represented the threat of nature in a fallen world, in contrast to the nature-worship concept that's now so prevalent.
The gerbil is human nature disguised as good and commendable, the scorpion is human nature as it really is—sinful and depraved and harmful to us.
The stones represent good deeds done for the Lord. The precious stones analogy was inspired by this passage in 1 Corinthians 3:12-15:
"If any man builds on this foundation using gold, silver, costly stones, wood, hay or straw, his work will be shown for what it is, because the Day will bring it to light. It will be revealed with fire, and the fire will test the quality of each man's work. If what he has built survives, he will receive his reward. If it is burned up, he will suffer loss; he himself will be saved, but only as one escaping through the flames."
The others didn't attempt suicide. They were brought to that world for other reasons not developed in the book.
Every book has a viewpoint character. Since this one was male he was of necessity developed more than the female characters.