Return
Zechariah writes at the time Judah is returning to their land from captivity in Babylon. Just as Jeremiah had said, after seventy years their captivity ends. God reminds them that He had sent prophets to warn their ancestors of their need to obey God, and instructs them that he doesn’t want them to make the same mistakes. Through visions, God promises that he will once again show mercy to his people.
The people hadn’t done anything to deserve God’s mercy. It remains to be seen if the people will return to Jerusalem and obey God or return to their old ways. God’s mercy for us is not based on what we do, but on God. Since God is God, we can depend on his character and promise regardless of what we do.