John Calvin Commentary 2 Thessalonians 1:9

"who shall suffer punishment, [even] eternal destruction from the face of the Lord and from the glory of his might," — 2 Thessalonians 1:9 (ASV)

Everlasting destruction from the face. He shows, by apposition, the nature of the punishment he had mentioned—destruction without end, and an undying death. The perpetuity of this death is proved from the circumstance that it has the glory of Christ as its opposite.

Now, this glory is eternal and has no end. Accordingly, the influence of that death will never cease. From this, the dreadful severity of the punishment can also be inferred, since it will be great in proportion to the glory and majesty of Christ.