Jamieson, Fausset & Brown

Which--Your enduring these tribulations is a "token of the righteous judgment of God," manifested in your being enabled to endure them, and in your adversaries thereby filling up the measure of their guilt. The judgment is even now begun, but its consummation will be at the Lord's coming. David (Psa 73:1-14) and Jeremiah (Jer 12:1-4) were perplexed at the wicked prospering and the godly suffering. But Paul, by the light of the New Testament, makes this fact a matter of consolation. It is a proof (so the Greek) of the future judgment, which will set to rights the anomalies of the present state, by rewarding the now suffering saint, and by punishing the persecutor. And even now "the Judge of all the earth does right" (Gen 18:25); for the godly are in themselves sinful and need chastisement to amend them. What they suffer unjustly at the hands of cruel men they suffer justly at the hands of God; and they have their evil things here that they may escape condemnation with the world and have their good things hereafter (Luk 16:25; Co1 11:32) [EDMUNDS]. that ye may be counted worthy--expressing the purpose of God's "righteous judgment" as regards you. for which--Greek, "in behalf of which ye are also suffering" (compare Act 5:41; Act 9:16; Phi 1:29). "Worthy" implies that, though men are justified by faith, they shall be judged "according to their works" (Rev 20:12; compare Th1 2:12; Pe1 1:6-7; Rev 20:4). The "also" implies the connection between the suffering for the kingdom and being counted worthy of it. Compare Rom 8:17-18.