The premise is interesting. An alien race makes first contact with the earth. Are they friendly or is Armageddon coming? The ship doesn't respond to earth's attempts to communicate. When they land, they speak Latin and the only person they are truly interested in meeting is the pope. The reason they didn't respond to any government contacts is they didn't come from the holy father. Catholic aliens in search of priests? What an intriguing premise.
The main character is an out of work Latin teacher who not only reads, but speaks Latin and so he becomes translator for the pilgrims who've spent hundreds of years crossing the universe in search of the Eucharist.