The first 2 vols. of Haight's Christian Community in History received enormous critical attention. Of vol. 2, the reviewer in the Journal of the American Academy of Religion concluded: 'This is a work of immense scholarship; yet it is wonderfully accessible in style and prose. It deserves to become the standard work in its field for some time to come.'

'Ecclesial Existence' is the constructive, systematic 'transdenominational' ecclesiology that serves as the conclusion to Haight's magisterial work. The key to Haight's ecclesiology is Bernard Lonergan's classic description of the movement from a classical-universalist consciousness to a historical-empiricist consciousness. Applied to ecclesiology, the classical-universalist approach is monistic and transcendental, while the historical-empiricist approach is pluralistic. Thus the first two volumes of Christian Community in History described the historical diversity of the church across its history (up to the Reformation in vol. 1) and among the churches (since the Reformation in vol. 2). By contrast, vol. 3 is an attempt to describe what the churches possess in common, i.e., to retrieve ecclesiological constants from history reaching back to scriptural origins in order to construct and portray the common ecclesial existence shared by the churches. In more traditional terms, it aims to find the apostolicity, the catholicity, and the unity amidst the plurality of the churches.