I won't pretend to know what this songs means or even implies as a whole, but for what it's worth, the last line is definitely in reference to Jesus. "delivering signs" is a phrase the Bible uses when talking about Jesus performing public miracles to prove his power, and "dusting from their eyes" is from a specific story where Jesus heals a blind man by spitting on the dust to make mud, then wiping the mud in the blind man's eyes. I think he references that specific miracle because the blind man had trouble understanding what he was seeing after he had been healed.
I won't pretend to know what this songs means or even implies as a whole, but for what it's worth, the last line is definitely in reference to Jesus. "delivering signs" is a phrase the Bible uses when talking about Jesus performing public miracles to prove his power, and "dusting from their eyes" is from a specific story where Jesus heals a blind man by spitting on the dust to make mud, then wiping the mud in the blind man's eyes. I think he references that specific miracle because the blind man had trouble understanding what he was seeing after he had been healed.