A Handbook of Theological Terms: Their Meaning and Background Exposed in Over 300 Articles

Harvey's little blue paperback is truly the seminarian's friend and I always keep a copy in sight whem I'm preparing a sermon or otherwise committing "God talk" to paper. An especially nice feature of the Handbook is that it points out distinctions between Roman Catholic and Protestant terminologies, important in these ecumenical times when we often dialog together and take courses at each other's colleges and seminaries.
There are glossaries and dictionaries that are more up to date but that's not always an advantage, because their trendiness comes at the expense of excluding theological terms that are centuries old and will be around for centuries to come. I'm not sure the lay person will have much need for the Handbook, but by all means if people at your church are arrogant enough to use terms like "Arianism," "Docetism" or "Prevenient Grace" without defining them, get yourself a copy and fight back!