Q: if a person can achieve and gain back his intellect (and maybe even receive atonement) by not going back to the bad that he did and by being very joyous, why is it that gehennom (purgatory) is constituted of fire and brimstone and not one big scene of repentance for the past and joy?
A: There is a gehennom of fire to rectify the unholy manifestation of the element of fire – enthusiasm for improper things. There is also a gehennom of snow to rectify the unholy manifestation of cold – laziness.
In the chasidic tradition, we learn that the old gehennom (as described in the holy writings) was burned. Now gehennom is the previous Garden of Eden – a place for repentance and joy. The new Garden of Eden is above and beyond what we can imagine.