My understanding is that hell isn't equal to heaven meaning that hell will at some point not exist. Also the vast majority of people don't reject Islam so Allah will judge them accordingly in the Quran. For those who rejected Islam, they will be punished. Hell(Jahanam) Cadaab(punishment); these two should not be confused. Disbelief and oppression are different Allah knows best. It could be possible that our understanding of forever is flawed as well because we view things from a finite world. Every believer will be able to testify for his loved ones condemned to hell.