Besides the point that if there was a fiery hell, God would be the one who made it in the first place...
In the Bible, the apostles and disciples, as well as non-believers, witnessed Jesus' miracles. Some of them were even granted the ability to perform miracles themselves. Peter walked on water and there were many witnesses to Lazarus' resurrection.
So obviously, according to your logic, they would no longer require faith or Jesus' sacrifice since they saw the miracles firsthand.
So they have no way to be cleansed and are doomed to hellfire.
Are you saying that God doesn't perform miracles because he doesn't want us modern folks to be doomed...but he had no problem dooming countless people back then by performing miracles?