“There is no believer whom the Son of God does not require to be His witness. In what place, at what time, with what degree of frequency, in what manner, and to what extent, we ought to profess our faith, cannot easily be determined by a fixed rule: but we must consider the occasion, that not one of us may fail to discharge his duty at the proper time” -John Calvin
The modern church needs to hear this in more ways than one. Not only do we need to be faithful witnesses of who Jesus is, we also need to hear that the focus of our witness is not in achieving results (although it certainly seems to be in much of the modern church). There's a strong pull into the deadly trap of pragmatism. Again, Calvin's words are nice because they're reflective of Acts 1:8 which says nothing of a results-based idea of evangelism. Of course we pray for and desire results...but we can't use them as a foundation to what we do.