Paul speaks about these people as if they were "double-talkers" or could say two things at once. He means the person says one thing but mean something else. AT: "should act properly and mean what they say" (See: [[rc://en/ta/man/translate/figs-metaphor]])
"They must continue to believe the true message God revealed to us and that we believe." This refers to a truth that had existed for some time but that God was showing to them at that moment. Paul speaks of true teaching about God as if it were an object that a person could keep with himself. (See: [[rc://en/ta/man/translate/figs-metaphor]])
Paul speaks of a person's knowledge that he has done no wrong as if that knowledge or conscience were clean. AT: "faith, knowing they have tried their hardest to do what is right" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This can be stated in active form. AT: "Other believers should approve of them first" or "They should prove themselves first" (See: [[rc://en/ta/man/translate/figs-activepassive]])