OET interlinear 2 TH 1:6

uW Translation Notes:

Note 1 topic: grammar-connect-condition-fact

εἴπερ δίκαιον παρὰ Θεῷ

if_indeed righteous_‹it_is› (Some words not found in SR-GNT: εἴπερ δίκαιον παρά Θεῷ ἀνταποδοῦναι τοῖς θλίβουσιν ὑμᾶς θλῖψιν)

Paul is speaking as if this were a hypothetical possibility, but he means that it is actually true. If your language does not state something as a condition if it is certain or true, and if your readers might think that what Paul is saying is not certain, then you could translate his words as an affirmative statement. Alternate translation: [Since you know that God is just] or [for God is certainly right]

Note 2 topic: figures-of-speech / metaphor

παρὰ Θεῷ, ἀνταποδοῦναι τοῖς θλίβουσιν ὑμᾶς θλῖψιν

(Some words not found in SR-GNT: εἴπερ δίκαιον παρά Θεῷ ἀνταποδοῦναι τοῖς θλίβουσιν ὑμᾶς θλῖψιν)

Here, to return means to cause someone to experience the same thing that they did to someone else as though the same action were bouncing back onto the people who did that action. Use a natural expression for this kind of reciprocal action. Alternate translation: [for God to afflict those who are afflicting you] or [for God to pay back those who are afflicting you] or [for God to do the same to those who are afflicting you]

Note 3 topic: figures-of-speech / abstractnouns

ἀνταποδοῦναι τοῖς θλίβουσιν ὑμᾶς θλῖψιν

˓to˒_repay ˱to˲_the_‹ones› oppressing you_all ˱in˲_tribulation

If your language does not use an abstract noun for the idea of affliction, you can express the same idea in another way. Alternate translation: [to afflict those who are afflicting you] or [to trouble those who are troubling you]