As a monk he believed language was sacred — especially that of the Zyryani or Permyak people who did not seem to have an alphabet.
So he very kindly invented one for them. (The fact that he could now translate the Bible into their language was just a coincidence of course.)
He appears to have been somewhat arty as well. His new alphabet was based on symbolic folk art, and he was also a dab hand at painting icons.
This all proved very popular and furthered his cause tremendously. Never underestimate the power of typography.