Casuistry - what is it? Simply put, it is the application of moral principles to practical situations. These are sometimes referred to as "cases of conscience." Yet, hear what Robert Lewis Dabney has to say about the benefit of private godly conference being the more proper place for such cases of conscience to be addressed, rather than the pulpit.
"I do not conceive that much of casuistry should he introduced into practical sermons. This belongs rather to the pastor's study than to the desk. The minute distinctions by which nice cases are to be adjusted, if they be addressed to a promiscuous company of persons not vitally interested in the particular problem, will be surely misunderstood by many. Thus they will minister to the morbid scruples of some consciences and to the license of others. And even in our private instructions love is the best casuist. Let the great principles of gospel love be presented with a breadth and warmth which, instead of dissecting, will dissipate the doubt." -- Sacred Rhetoric; Or, A Course of Lectures on Preaching, p. 63.