Below is an article that reviews 10 free timeline generators. Read through the short reviews and choose the best one for your class.
The Tiki-Toki timeline generator is already used in some Theology classes. Check out this sample timeline created by Diana Haney, “St. Iggy and the Jesuits”: http://www.tiki-toki.com/timeline/entry/492586/Saint-Iggy-and-the-Jesuits/