Renaissance Siena, Italy (Christian??) Fiction Series Good vs Evil

I read these books about 15 years ago - female hero, Christian themes (gifts of the holy spirit, etc), thriller, good vs. evil. The author of the series is a woman and I didn't pick up on the fact that it was a Christian series initially (despite the religious overtones; it just fit well with the time period and the plot). I believe there are four or five books in the series.

Maybe the Stravaganza series by Mary Hoffman? They are YA fantasy from about the right time period. I think the second one (Stravaganza: City of Stars) is set in a city based on Renaissance Siena.