To find resources on Christian art and iconography in the catalog, select the "Subject" search on the Advanced Search page. Some of the terms you would use include "Christian art," "iconography," or "Christian symbolism."
Depending on your topic, you can narrow down your searching even further by adding subdivisions. For example, under the "Christian art" subject search, you could focus the search in these different ways:
You could also change the results by the format of the book, adding terms like "Encyclopedias," "Handbooks, manuals, etc.," and "Dictionaries" to the end, bringing back just those types of items.
Broadening your search could be beneficial as well. Here are some general topics that could provide worthwhile books:
BR- Christianity
BS- The Bible
BX- Christian Denominations
N- Visual arts
NA- Architecture
NB- Sculpture
ND- Painting
NX- Arts in general
The Bible and the Saints by 
Christian Iconography; The History of Christian Art in the Middle Ages by 
Church Monastery Cathedral by 
Church Symbolism; An Explanation of the More Important Symbols of the Old and New Testament, the Primitive, the Mediaeval and the Modern Church by 
Iconography of Christian Art by 
The Oxford Companion to Christian Art and Architecture by 
Saints and Their Symbols by 
