Zechariah 13:9 prophesies that a "third part" would be brought through the fire to be refined like silver and gold. This imagery represents the process of removing dross—the impurities of Old Covenant legalism and worldly reliance—through suffering.
Peter, writing to the first-century remnant, explained that the "fiery trial" they were enduring was for the "testing of your faith," which is "more precious than gold that perishes" (1 Peter 1:7). The persecutions under the Jewish Sanhedrin and the Roman Emperor Nero were the specific "fire" that refined the early Church, ensuring they emerged as the pure, vindicated people of God after AD 70.