"he seriously told them." Here the word "testified" and "begged" share similar meanings and emphasize that Peter urged them strongly to respond to what he was saying. Alternate translation: "he strongly urged them" (See: [[rc://en/ta/man/translate/figs-doublet]])
The implication is that God will punish "this perverse generation." Alternate translation: "Be saved from the punishment that these wicked people will suffer" (See: [[rc://en/ta/man/translate/figs-explicit]])
Possible meanings are 1) Peter was urging people to let God save them. Alternate translation: "Let God save you," or 2) Peter was simply urging them in a general way to avoid being punished. Alternate translation: "Save yourselves" or "Flee" or "Escape" (See: [[rc://en/ta/man/translate/figs-activepassive]])