Francis Schaeffer on Heresy and Separation

This, I believe, was spoken at the Berlin Congress:

Let us never forget that we who stand in the historic stream of Christianity really believe that false doctrine, at those critical points where false doctrine is heresy, is not a small thing. If we do not make clear by word and practice our position for truth as truth and against false doctrine, we are building a wall between the next generation and the gospel. And twenty years from now, men will point their finger back at us and say of us, this is the result of the flow of history.