John Calvin on 2 Thessalonians 1:9

9. Everlasting destruction from the face. He shews, by apposition, what is the nature of the punishment of which he had made mention — destruction without end, and an undying death. The perpetuity of the death is proved from the circumstance, that it has the glory of Christ as its opposite. Now, this is eternal, and has no end. Accordingly, the influence of that death will never cease. From this also the dreadful severity of the punishment may be inferred, inasmuch as it will be great in proportion to the glory and majesty of Christ.