It looks like you're using Internet Explorer 11 or older. This website works best with modern browsers such as the latest versions of Chrome, Firefox, Safari, and Edge. If you continue with this browser, you may see unexpected results.
The history of ancient Christianity is an expansive topic, incorporating hundreds of years of hundreds of authors writing thousands of books. Imagine searching through all that to find one passage relevant to your research! Indexes aggregate historical data and organize it in easier to find ways, much like a book index.
The most important characteristic of an index is the data: subject, author, works, citations, etc. Though many indexes are now online, oftentimes you may need to read an index's introduction to learn how to search it effectively.
Indexes for Early Christianity
Biblia patristica by Centre national de la recherche scientifiqueOnline available. 7+ volumes. The index des citations et allusions bibliques dans la littérature patristique indexes all Biblical citations and allusions in patristic literature. Provides Biblical passage cited, plus the exact reference to the book employing the citation.
Clavis Patrum Graecorum by Mauritii Geerard6+ volumes. Online available. Includes Christian writings in Greek through 8th century. Lists known authors, works, editions, and (some) secondary literature. Cross-referenced with Corpus Christianorum.
Clavis patrum latinorum by Eligius Dekkers15+ volumes. Online available.Includes Christian writings in Latin through 8th century. Lists known authors, works, editions, and (some) secondary literature. Cross-referenced with Corpus Christianorum.