A.T. Robertson Commentary 2 Thessalonians 1:5

"[which is] a manifest token of the righteous judgment of God; to the end that ye may be counted worthy of the kingdom of God, for which ye also suffer:" — 2 Thessalonians 1:5 (ASV)

A manifest token of the righteous judgment of God (ενδειγμα της δικαιας κρισεως του θεου). Old word from ενδεικνυμ, to point out, result reached (-μα), a thing proved. It is either in the accusative of general reference in apposition with the preceding clause as in Ro 8:3; 12:1, or in the nominative absolute when ο εστιν, if supplied, would explain it as in Php 1:28. This righteous judgment is future and final (verses 6-10).

To the end that you may be counted worthy (εις το καταξιωθηνα υμας). Another example of εις το for purpose with first aorist passive infinitive from καταξιοω, old verb, with accusative of general reference υμας and followed by the genitive της βασιλειας (kingdom of God). See 1 Thessalonians 2:12 for

kingdom of God .

For which ye also suffer (υπερ ης κα πασχετε). Ye

also as well as we and the present tense means that it is still going on.