He gave them good reason to believe that, too. A savior of souls would have no need to be born in Bethlehem, and descended from David but not Solomon.
“That meant when their king came, with one mighty stretch of his arm, he would wipe away their enemies,” he said. “But John recognized that Jesus was the one we had been waiting for all those centuries. And John, upon seeing Jesus approach, said, ‘Behold, the lamb of God,’ acknowledging Christ.”
How do we know he said that? Oh, it's in the book of John, written decades later."I knew it all along." But somehow he and Jesus couldn't get it across to anyone else. Why? Most likely explanation: he didn't know any such thing, and all this after-the-fact "I tried to tell them" business is exactly what it usually is.