“The gospel is Good News. The message determines the medium. There is a clear logic to Paul’s argument in Romans 10, where he contrasts “the righteousness that is by works” and “the righteousness that is through faith” (Rom. 10: 5-6 NIV). We were redeemed by Christ’s actions, not ours; the Spirit applies this redemption to us here and now so that we are justified through faith apart from works; even this faith is given to us through the proclamation of Christ. Since this gospel is a report to be believed rather than a task for us to fulfill, it needs heralds, ambassadors, and witnesses.
The method of delivery is suited to its content. If the central message of Christianity were how to have your best life now or become a better you, then rather than heralds we would need life coaches, spiritual directors, and motivational speakers. Good advice requires a person with a plan; Good News requires a person with a message. This is not to say that we do not also need good advice or plans but that the source of the church’s existence and mission in this world is this announcement of God’s victory in Jesus Christ.”
-Michael Horton (Christless Christianity)