As Paul continues, he talks about God being just.
"God is right" or "God is just"
"to return" here is an idiom meaning "to pay back" AT: "for God to pay back with affliction upon those who afflict you" (See: rc://en/ta/man/translate/figs-idiom).
You can make it explicit that God is the one who provides relief. AT: "for God to provide relief to you" (See: rc://en/ta/man/translate/figs-ellipsis)
"his powerful angels"
"He will punish with blazing fire those who do not know God and those who" or "Then with blazing fire he will punish those who do not know God and those who"