This is personification, referring to the thunder as the voice of God. AT: "voice, which was as loud as thunder" or "very loud voice" (See: [[rc://en/ta/man/translate/figs-personification]])
This is an exaggeration to emphasize that the lightning lit up everything the writer could see. AT: "lightning lit up everything as far as you could see" (See: [[rc://en/ta/man/translate/figs-hyperbole]])