If a more advanced student wants to begin thinking about the task of Old Testament theology, they would do well to read Hasel’s “Old Testament Theology: Basic Issues in Current Debate.” Be sure to get the fourth edition. It is substantially different than the previous editions.
For the advanced student, “Old Testament Theology: Flowering and Future” by Ollenburger gives commentary and excerpts from Old Testament theological writings that would prove very helpful. Many of the entries in this volume are not evangelical.
In addition, all of the recommendations below are really for the intermediate to advanced student, but the well-read undergraduate might find them helpful. This category was particularly difficult in that there are many superb non-evangelical theologies, but below are four I would recommend:
“Old Testament Theology” by Paul House
This is a book-by-book treatment of Old Testament theology. House does a good job of introducing students to major themes and theological content in each Old Testament book.
“Dominion and Dynasty: A Theology of the Hebrew Bible” by Stephen Dempster
Dempster approaches Old Testament theology from a canonical perspective in this entry. His discussion of the content of books, and groupings of books, is very helpful.
“Everlasting Dominion: A Theology of the Old Testament” by Eugene Merrill
Merrill’s study is a culmination of his years of thinking through the Old Testament and has serval insightful and helpful discussions of themes and individual texts.
“Old Testament Theology: A Thematic Approach” by Robin Routledge
Routledge approaches Old Testament theology through a series of themes in this book, giving an overview of how a thematic approach works within Old Testament theology.