What has happened to make evangelicalism a shell of its former glory? Dallas Willard points to one main reason as the loss of the identity of Jesus as our Teacher.
Salvation by grace through faith is one of the great truths that emerged in the Protestant Reformation. But grace is so misunderstood; we tend to think of grace as the opposite of effort. If effort is involved, then it was not grace.
But this just isn't true. Effort isn't the opposite of grace, earning is. In fact, grace stimulates a ton of effort. Willard cites the great missionaries of the 19th century as examples. But people today misunderstand grace as no effort.
A second factor he mentions is one of the results of the modernist/fundamentalist debates. "Jesus as Teacher" sometimes became liberal modernist code-speak for Jesus is only human. So fundamentalists rejected the phrase. Unfortunately that also meant they eventually rejected the truth--that Jesus is our Master Teacher, and we are to be his disciples or apprentices in how to live life. Evangelicalism by and large no longer teaches that we are to be disciples of Jesus as Christians. Most churches even allow for someone to be a Christian without being a disciple.
Jesus came to do more than help us manage our sin, obtain forgiveness, and escape hell. He came to teach us how to live.