Lowest-Common Denominator Witness
The difference between the two groups centers on the question of the nature of the witness to the Christian faith as this is given by Fundamentalists or Evangelicals. The nature of that witness we have found to be one of compromise with unbelief at every point. A common witness is, therefore, we believe, the same in effect as a compromising witness.
A common witness is of necessity the lowest common denominator witness. This would be true even if, in any given organization, the representatives of the Reformed Faith were in the majority. Any witness to the Christian faith must be positive as well as negative. It is always both at the same time. It cannot be otherwise. There is no intelligible witness against the wisdom of the world except in the name of the wisdom of God. And a common witness involves, therefore, a common responsibility for the positive affirmations of the faith as well as the negations against unbelief. Now the positive affirmations of Evangelicals are, without exception, confused and compromising in character. It is for the confused and compromising witness of Fundamentalism that Reformed Christians become co-responsible in any effort at giving common witness to the world.
Cornelius Van Til, The Articles of Cornelius Van Til, ed. Eric H. Sigward (Labels Army Company: New York, 1997)