The early church fathers taught:
"As two advents of the Lord are indicated in the
Scriptures, also two forerunners are indicated;
the first was John the son of Zacharias. He first
fulfilled the course of the forerunner. But since
the Saviour is to be manifested again at the end
of the world, it is a matter of course that His
forrunners must appear first, as he says in
Malachi. . . . "