Basic principle of preaching activities
It is usual for the devotees to become very enthusiastic whenever they are questioned concerning the Almighty Personality of Godhead. That is the sign of a pure devotee of the Lord. Such discourses on the transcendental activities of the Lord purify the atmosphere in which such discussions are held, and the devotees thus become enlivened while answering such questions. It is purifying both for the questioners and for one who answers the questions.