The level of insanity, cruelty and plain old sadism required should make us thankful that it doesn't exist.
Tonus
If God truly is love, as the scriptures repeatedly claim, non-existence is a more logical punishment. To return to dust. To disintegrate you so as to never be conscious again.
In the old testament God is shown 'cutting off' the wicked, simply ending their life. Never once does he instruct Joshua for example to round up the Canaanites and torture them with fire. We do however read how God detested the Canaanite ritual of burning children alive as a sacrifice to their gods, an act that never rose in God's heart to begin with, according to Scripture.
Jesus also stated "if you, being wicked, can show love to your children, how much more so will God show you love".
Non-existence is a more humane state of being than a state of eternal torture. We as human beings agree on this. We cannot be more humane than God.