Berger begs to differ, although not with Luhrmann's characterization of the Evangelical experience of God. Instead, Berger notes that American has regularly re-envisioned God since the days of Jonathan Edwards in the mid-eighteenth century. I might not go that far but certainly by the turn of nineteenth century with the institutional rise of Unitarianism and then the Second Great Awakening we see strands of American Christian spirituality that stand in marked contrast to the confessional standards that had informed their forebears. What Christian Smith describes a "moral, therapeutic deism" (see here and here) has more and more come to describe virtually the entirety of the American Evangelical experience of God and may have penetrated some quarters of even a putatively confessional denomination like the Presbyterian Church of America.
Also characterizing the "nice" God of American Evangelicals--and perhaps an effect of it--is the felt need to "market" Christianity in the most inoffensive, undemanding way possible. Churches become little more than places where some nice people hang out to experience their nice God. And when pure niceness fails, modern business marketing is called on to increase attendance.
Both this re-visioned God and the business model of the church characterized the Crystal Cathedral. (See here.) That each eventually proved unable to keep that church going should come as no surprise if Berger's final comment in his review is true:
There are some grounds for thinking that American society is becoming less open and that its power is in decline. Such developments would affect every dimension of the culture, including the religious one. It is possible that the smiling God of Evangelicalism will develop more of a scowl.