Here are two direct quotes from Michael Horton:

"The contributors to Power Religion would be quick to note that these disciplines [sociology, psychology, and politics] are not in themselves evil or unnecessary ... None of the authors suggests that those who support Christian political activism, the signs and wonders movement, the church growth movement, the therapeutic movement, or sensational or potentially authoritarian schemes, are non-Christians or enemies of the faith masquerading as disciples of Christ ... [That is a large part of the problem today -- the acceptance of everyone as genuine Christians, regardless of their doctrinal fruit.] In fact, none of us suggests that there is nothing to learn from these various movements. Speaking for myself, I know that my own Christian faith and life would be the poorer without interaction with some of my close friends who are charismatic, for instance. Likewise, I have admired the zeal of some church growth leaders ... miracles, philosophy, corporate and psychological insights, and political positions may well be part of the life of any Christian, [although] they are weak substitutes for the gospel" (Jacket & pp. 14-15, 333.)

"... while we oppose the 'end-run' around the cross that psychology often performs when it assures non-believers that God is on good terms with them, we do not condemn psychology itself, only its attempt to usurp the place of God. Psychology is a very helpful and necessary tool when used wisely"