Books titles (as well as many other types of material) can be found in the CLIO Catalog, the online catalog of the Columbia University Libraries. CLIO includes Barnard Library, but not Teachers College, Jewish Theological Seminary, or the Law Library.
Burke Library at Union Theological Seminary (located on the northwest corner of Broadway and 120th) has the largest collection of books on religion available in the Columbia Library System. Jewish Theological Seminary (located on the northeast corner of Broadway and 122nd) also has a library that can be used, but Barnard/Columbia students must pay $20 per term for a library card.
Commentaries are a key part of religious studies in academia when focusing on the Judeo-Christian Bibles. These often analyze, explain, and interpret portions of scriptural works, often chapter by chapter. Many commentaries are applicable for both Jewish and Christian Bible studies, as there is much overlap in scholarship.
While most of these will be housed in the Burke Library at Union Theological Seminary (UTS), Butler's Ancient and Medieval Reading Room, located on the sixth floor of Butler Library, also houses many works relevant to biblical studies.
These books may help in writing about different aspects of Religion.