For people: [[John Calvin]], unless others by that name exist, in which case the activity for which the individual is best known should be bracketed, e.g., [[John Calvin (reformer)]] (not [[John Calvin (scholar)]], [[John Calvin (theologian)]], etc.)
For clergy: (minister), (deacon), (priest), (bishop)
For scholars: (theologian), (philosopher)
Other possibilities: (author), (martyr), (missionary), (religious)
For other subjects: The simpler the title the better, with redirects or disambiguation pages, as necessary.