There are many synonyms for the phrase "loquacious mad-priest," which refers to a talkative and possibly eccentric religious figure. Some alternative phrases could include "chatty ecclesiastic," "verbose clergyman," "garrulous holy man," or "rambling minister." Each of these creates a slightly different image of the character in question, but all convey a similar idea of someone who is outspoken and perhaps a bit unconventional in their behavior or speech. Whether you're writing a story or just looking for a creative way to describe a particularly talkative priest, there are plenty of options to choose from.