The Gospel...

...is the power of God unto salvation for all who believe.  If we really believe that we will act like it and the gospel will fairly ooze out our pores.  If we don't really believe it we will think we need to help the gospel in evangelism by attracting people with glitz and action or by helping the gospel in our own lives by adopting a legalistic attitude toward rules.  Check out another good post on this by Jared Wilson.