There is quite a bit of Medieval Art "reflecting a religious perspective"(and quite a few other perspectives) as well as Renaissance art; in fact one could argue that a significant portion of historical art is religious or reflects a religious perspective. If you have institutional access to the Index of Christian Art(your school's librarian should be able to help you with this) you will have more religious art than you can shake a finger at at your disposal; at the very least you could look at for instance the famous Romanesque portals of Southern France like Autun or Vezalay, manuscripts like the Luttrell Psalter or the Bernward Gospels, or even the cathedrals of Reims or Chartes. In addition, virtually every museum website puts a substantial part of its collection online so any museum with a good medieval collection will have lots of art for you to pick from that you can look at; notable American collections include the Walters, the Pierpoint Morgan Library, the Metropolitan Museum of Art, and the Cleveland Museum of Art.

On the topic of religious art in Islam: This question is somewhat difficult; for a general treatment of the topic see Aisha's Cushion and The Transformation of Islamic Art During the Sunni Revival for an investigation of the relationship between Islamic thought and medieval Islamic architecture.

EDIT: Do you have something specific in mind here? All religious art everywhere is quite a large amount of material.