D.A. Carson

  So what we need, then, is a prayer life that thanks God for the people of God, and then tells the people of God what we thank God for.
  This obvious lesson may have a bearing on the rising incidence of applause in many Western churches.  Applause used to be unknown.  Then it came to be deployed after special music.  Now it is sometimes heard punctuating sermons.  This is, I think a regressive step.  True, some might consider this to be a kind of cultural equivalent to a voiced "Amen!"  I take the point, and would not want to introduce new legalism by banning applause outright.  But the fundamental difference between "Amen!" and applause must be noted: the "Amen!" is directed to God, even if it serves to encourage the person who is ministering, while applause in our culture signals approval of the performer.  God is left out, and the "performer" may the more easily be seduced into pride.  This is one of the several ways by which the rules of entertainment world have subtly slipped into corporate worship and are in danger of destroying it from within.

D.A. Carson, A Call to Spiritual Reformation, pg. 88