So far as we know, the souls of the wicked dead are still in the hell compartment of the underworld and will remain there until the second resurrection, when they will return to the earth, get their bodies, and then go to the great white throne judgment. After judgment, they will be sentenced to the second death, which means that they shall die again in the sense of losing their bodies again. As disembodied spirits, they will be cast into the lake of fire, gehenna , the final hell, to suffer in flames forever. As soul and spirit are impervious to flames, this explains how the wicked, after being disembodied again by the second death, can exist forever in literal fire. See less