A problem similar to that of verse 11 exists also in verse 12. Here translations are divided between expression the idea of purpose (Revised Standard Version “so that all may be condemned,” cf. Moffatt Jerusalem Bible New English Bible Biblia Dios Habla Hoy Traduction œcuménique de la Bible) and the idea of result (Good News Translation the result is, cf. Phillips Translator’s New Testament Bijbel in Gewone Taal Bible en français courant). Knox and Die Bibel im heutigen Deutsch divide the sentence in such a way that neither relation is explicit. Here, as in verse 11, the element of purpose fits the context better. Paul is not only saying that unbelief results in condemnation, but that this is all part of God’s purpose. To indicate the concept of purpose, it may be necessary to refer back to the activity of God mentioned in verse 11, for example, “God did that so that all … will be condemned.” Result may be expressed specifically as “hence all … will be condemned.”
As in verse 11, believed includes an element of personal truth (like love the truth in v. 10). The Hebrew word for “truth,” which often underlies New Testament usage, refers to that which is firm and can be relied upon.
As in the case of verse 10, it may be necessary to render the truth as “the true words” or “the true message,” and even to add something about the content of the message, namely, “about our Lord Jesus.”
“To take pleasure in” something does not merely mean to enjoy the object. As in Mark 1.11, there is an element of will and choice. In the present verse, therefore, Jerusalem Bible translates “chose wickedness” and Barclay has “deliberately chose sin.” Have taken pleasure in sin may be rendered as “are happy when they sin,” or “sin and are glad that they have sinned.” Perhaps the simplest equivalent in some languages is “like to sin.”
In a number of languages it may be necessary to reverse the order of the negative and positive statement and say, for example, “the result is that all who like to sin and who do not believe the truth will be condemned.”
The Greek word translated condemned by itself means simply “judge,” but here the context requires the meaning condemned. Compare Romans 2.12b, where there is a close parallel with “are lost” in verse 12a; cf. also 1 Corinthians 11.31-32. The passive expression will be condemned may be made active by introducing God as the agent, for example, “God will condemn them,” “God will pronounce them guilty,” or “God will say, You are guilty.”
Quoted with permission from Ellingworth, Paul and Nida, Eugene A. A Handbook on Paul’s Second Letter to the Thessalonians. (UBS Handbook Series). New York: UBS, 1976. For this and other handbooks for translators see here .