The thesis discusses the use of the literary genre Theology of the New Testament (TNT) to overcome the diversity in New Testament theologies uncovered by post-Enlightenment biblical-critical methods. Following an initial sketch of the problem caused by NT diversity, an overview of various strategies roughly classed as deleting diversity or unifying diversity is presented. Attention then turns towards a review of TNTs published since 1990 using their approach to NT diversity as the thematic focus. TNTs are examined according to the extent that they are able to both preserve textual alterity and integrity whilst rendering NT polyphony theologically fruitful. The conclusion of this review suggests that any kind of unity relating to the NT canon can plausibly only be located either prior to the texts in some postulated shared hermeneutical presuppositions of the NT writers and/or in the the act of theological construction by the contemporary reader. The dialogical TNT model is advanced as the best option for theologically interacting with NT diversity. The second part of the thesis provides an ethical, hermeneutical, and theological justification for the dialogical TNT model with reference to Gadamerian philosophical hermeneutics and Bakhtinian theory. The contribution of the model is then discussed in relation to three key issues facing the TNT: its relation to Theologiegeschichte as a competing model; its relation to systematic theology and the question of biblical normativity; and its relation to the transformation of the TNT genre within the recent Biblical Theology of the NT genre. Ultimately, the usefulness of the TNT genre as adequate for the constructive task of Christian theology is called into question, since the dialogical model regards the quest for a NT “unity” that can define a stable Christian identity as hermeneutically redundant and theologically limited.