The Oxford Dictionary of the Christian Church

One of the great benefits of the Logos 4 libraries is serendipity. Here specifically I’m thinking of finding books in your library that you didn’t really know you had, but once you find them you’re so glad you’ve got ’em you don’t know how you studied without them.
For me, one of these wow-I’m-glad-I-found-it books is the Oxford Dictionary of the Christian Church (ODCC). It comes in the Scholar’s LE, Silver LE, Gold LE, Platinum LE and Portfolio LE libraries for Logos Bible Software.
And the ODCC is a gem. Clearly written. Top-notch scholarship. Recent. Relevant. Almost 2000 pages of excellent reference material that covers a wide array of topics and ideas. The ODCC is simply stunning.
One of my newfound roles here at Logos is that of columnist, where I’m responsible for the Thoughts from the Church Fathers column for Bible Study Magazine. As I work on each new column, the patristic entries in ODCC have been very helpful. They provide a great introductory sketch both of familiar figures (e.g. Augustine) and figures you might never have heard of (e.g. Cyril of Jerusalem). They lay out the contour and timeline while highlighting major issues, typically with links to entries describing these issues or debates. It’s like a one-stop shopping trip, and it is awesome.
But the patristic entries (while my favorite) are only one aspect of the ODCC. There is all sorts of stuff in it: Theology, Patristic scholarship, Churches and denominations, Church calendar and organization, Biographical entries, and more.
If you’ve got ODCC (just fire up Logos 4 and type ‘ODCC’ in the command box or in the Library to see if you have it already), then you owe it to yourself to check it out and look at some articles the next time you’re working on something (especially if you see any reference to particular church fathers).
If you don’t have ODCC, then you should check it out and, if the time is right, add it to your library. Or compare the cost of buying ODCC outright ($150 retail) with the cost to upgrade to at least Scholar’s LE. If your upgrade cost is close to (or under) $150, and you don’t have ODCC, then you could really end up getting a great deal on the upgrade — ODCC plus whatever else is in Scholar’s LE that you don’t already have.
Update: In the comments, it is noted that the 3rd edition of ODCC (from 1997) has been republished in paperback by another publisher. The edition in Logos Bible Software is the 2005 revision of the 3rd edition, which has some significant differences from the third edition. Below is an excerpt from the Note on the Revision of the Third Edition in the front matter of the 2005 edition:

The revision of the third edition was planned as a modest exercise, designed to incorporate changes which would not fit into successive reprintings and to include some updating wanted for a projected online version. The original pagination was to be preserved, and a limited number of short new articles were to come at the end. Until after production had been put in hand, I expected the pagination to be generally retained and I worked within this constraint. Nevertheless, the scope of the revision widened and I made a large number of small changes to reflect events and shifts in scholarly opinion over the last eight years or so, juggling with the text to fit in the new material. In some cases I commissioned completely new articles, impressing on their authors that they must be of the same length as the material they replaced. Inevitably, however, the main changes are in the bibliographies.

F. L. Cross and Elizabeth A. Livingstone, The Oxford Dictionary of the Christian Church (3rd ed. rev.; Oxford; New York: Oxford University Press, 2005), ix.