I suggest that most of the people who want be viewed as post- evangelicals have felt the need to free themselves from the shackles of the form of evangelicalism they inherited from their own tradition. I slowly had to free myself from the evangelicalism of the Inter-Varsity group I was converted in. And I discovered that genuine evangelical good news was far bigger than the narrow explanation I had adopted. I find some of the positive aspects of postmodernism very helpful. The reason is that post-modernism refuses to allow any one model to be privileged, even the form of Evangelicalism we were stuck with.
All models are hypothetical.
That suggests that God allows his children the freeedom to look at, and try out if we insist, all sorts of ways of looking at the good news of what life is about. That means we need to allow each other to compare and contrast different models. And the first step is for genuine Evangelicals to agree that God is not bound to any one form of Evangelicalism. We are free to learn from Calvinistic and Wesleyan models, Greek Orthodox and Lutheran, Mennonite and Charismatic models, Anglicans and Baptists. In the Evangelicalism of the Cambridge University InterVarsity group where I was was nurtured from 1947 to 1950, C.S.Lewis was viewed as a dangerous Liberal who must never be invited to speak at any of our meetings.