Most Bible quilts I've seen are samplers, with each block representing a person, place, or event in the Bible.
This site used to have free Bible blocks, but now you can order PDF patterns:
http://members.shaw.ca/kigraham/index.html
This site started with "Women of the Bible" quilt based on a devotional focusing on the same theme and has expanded to other themes.
http://www.patternsoffaith.com/
You could also do something similar yourself. You could use a block library (quilterscache.com comes to mind as an easy online source) and select a variety of blocks based on their names.