It is by no means appropriate for every person to discourse about God. Indeed, it is not for everyone. The subject is not as cheap or vulgar as that! What is more, it is not proper to do so before any audience, at any time, or on every point; only on certain occasions, in the presence of select people, and within certain limits. It is not for everyone, because it is lawful only to those who have been duly tested and are past masters in meditation, who have been purified beforehand in both soul and body; or at least are in the process of being purified. It is never safe, we might safely say, for the impure to handle what is pure, no more than it is safe for weak eyes to be fixed on the Sun’s rays. So what is the permissible occasion? It is when we are free from all external defilement or agitation, and when our guiding spirit is not confused with troubling or wandering images, which would be like persons who mix up good writing with bad, or sweetly perfumed ointments with stinking filth. One needs true peace to know God and, when we can find the appropriate time, to discern the high road of the divine matters in hand. So who are the people for whom such things are permissible? They to whom the subject is of real moment, and not those who make it a subject of pleasant domestic chatter, or gossip after the races or the theatre, after concerts, or dinner parties: not to mention still lower employments.

John Anthony McGuckin. The Path of Christianity: The First Thousand Years (Kindle Locations 23220-23233). InterVarsity Press. Kindle Edition.