“They will be punished with eternal destruction (olethron aionion)” (2 Thes. 1:9). Aionios means enduring through or pertaining to a period of time. Both the noun and the adjective are applied to limited periods. Thus the phrase eis ton aiona, habitually rendered forever, is often used of duration which is limited in the very nature of the case.
The words translated “eternal”, “eternity” or “forever” in traditional Bible translations do not, in fact, mean eternity or eternal in the sense of endless duration, but “age” or “age-enduring”.