Robert E. Webber was one of the earliest proponents of the "ancient-future faith" movement. He advocated that Protestants and evangelicals recover the practices, formations and traditions of the early Church. "Common Roots", originally published in 1978, would be the first of his many books on the subject. This book broaches on the topics of the Church, worship, theology, mission and spirituality. Webber's chief concern is that evangelicalism on its own, devoid of Christianity's historical roots, is not fully mature.
Webber was very well-acquainted with the various Christian traditions. On p. 56-57 he helpfully provides a summary of the various Christian subcultures that exist among Protestantism, listing such groups as "Reformed evangelicalism", "holiness evangelicalism" and "dispensational evangelicalism." He draws upon the historical approaches of various Protestant camps, whether it be Calvinism's call to transform culture or the fundamentalists' puritanical rejection of much of contemporary culture, in order to both critique and affirm evangelicalism's vision, practice and mission. For instances, he criticizes those liberal Christians who make God into a process (e.g. God is the process of political emancipation) as well as those Christians who reduce the worship of God to a merely emotional experience with no regard for the mind and theology.
Some of what Webber advocates may sound to evangelicals like a return to Rome. He stresses the importance of the apostolic witness in receiving the historic faith and desires that evangelicals have a better grasp of the historicity of the Church. He repudiates an individualistic interpretation of the Bible in favour of the historical interpretation of the Church as always taught. He urges that worship be focused on both Word AND sacrament, something that some denominations, such as Southern Baptists (who rarely even USE the term "sacrament"), might take umbrage with.
However, Webber does not suggest that Protestants swim the Tiber. He recognizes the importance and validity of the Reformation but also acknowledges that schism has led to an impoverishment among many Protestants who were so eager to reject Catholicism that they inadvertently spurned many of the profitable practices and traditions that Catholicism had developed (such as the spiritual practices of the monastics and mystics).
Webber runs into some difficulty however. While he is conciliatory and charitable, declaring that Christians must appreciate the various contributions to truth that the diverse array of Christian heritages bring (every Christian tradition brings a certain angle to the picture in order to make it a more complete picture), in some cases it is clear he DOES reject some Christian beliefs. For instance, on p. 249 he sharply rebukes contemporary Christian music that downplays God's omnipotence and majesty in favour of a "God is my friend" mentality. But perhaps that is the image of God our twenty-first culture needs, a culture that is "bowling alone", that suffers from an epidemic of broken homes.
In discussing the mission of the Church, Webber chastises many evangelicals for vainly importing Western theology into the Third World. He laments that missionary efforts, while done with the best of intentions, often forced the convert to abandon their native heritage in order to become a Christian; in so doing, the convert was also saddled with an entirely new Western culture (thus, practices common to their native culture that clashed with evangelical orthodoxy were banned, such as polygamy; Webber observes that this is in contrast to the accomodationism of Catholicism that affirmed what was good in the foreign culture, seeing every individual as imprinted with the "image of God" and thus good, leading to a laissez-faire attitude towards some primitive practices that offended Protestant sensibilities). Webber stresses the need for context in mission; he asserts that evangelicals need to (and NEEDED) to proclaim the Gospel according to the context that they were in. Thus, the proclamation of the Gospel would look a lot different in the rural towns of America during the Great Awakening than it would among the sub-Saharan African tribes during the colonial age. However, if what Webber says is true and the contextualization of the Gospel is needed in order to be effective, then some of the historic practices of the Church are no longer familiar or even desirable among Western Christians today. For instance, the Church has historically waffled on the question of female ecclesiastical leadership. While many would claim Junia is an example of a woman leader in the early Church, she had the misfortune of going through a sex-change centuries after her death, perhaps in order for later church leaders to deny women leadership roles in the Church. Today, debates still rage between complimentarians and egalitarians but Western culture seems mostly on the side of the egalitarians. While women have historically been denied high positions of leadership in the Church, is this something we wish the Church to uphold today? As well, noted sociologist David Martin has observed that Pentecostalism represented one of the hallmarks of the American ideal by being "democratic". This would clash with more hierarchal churches that have historically employed a threefold ministry of bishop, priest, deacon. Similarly, the traditional vestments of the Catholic, Orthodox and Anglican clergy appear thoroughly antiquated besides the modern suit and tie of a pastor such as Timothy Keller. While one could argue that traditional vestments should continue to be worn by clergy because of their historicity, their use creates a dichotomy in the congregation, separating clergy from laity, though all are equal brothers and sisters in Christ (and as mentioned, democracy is one of the West's most cherished values; differences in clothing embody a hierarchy).
There is much to admire and affirm of Webber's vision. His call to recover the Christian conception of time is commendable and we can see some of that happening now as Lent is being practiced by Protestants as well as Catholics. He has a far higher view of the Church than many evangelicals today, rejecting the cancer of individualism that isolates believers and allows them to practice a personal faith with a "personal Jesus", in favour of a view of the Church that sees it as Christ's Body in the world today. Additionally, many of Webber's suggestions seem to have been embraced by evangelicals today; for instance, Protestants such as the late Dallas Willard and Quaker Richard J. Foster have written extensively about the classic spiritual disciplines, re-introducing these practices into the Protestant Church, even to those denominations that have a very low ecclesiology. Throughout "Common Roots", Webber warns of how the early Church had to confront Gnostic foes that shunned the physical in favour of the spiritual, a distortion that has stricken much of evangelicalism today, but appears to be receding, with such books as N.T. Wright's "Surprised By Hope" which recovers the early Church's understanding of Heaven as a transformed and restored Earth. As well, Webber's legacy has been carried on by thinkers such as James K.A. Smith who in his Cultural Liturgies series writes of the importance of form in worship.
I need to write up a real review eventually, but for now, if you are interested in Anglican/Catholic theology as an Evangelical, this is one of the early books that talked about why that move might be attractive. Originally written in 1978 it is surprisingly relevant to what is going on today among many that I know.