[Jean-Francois Lyotard's] problem with metannaratives has nothing to do with the scope of their claims — that they are "large-scale" stories of "universal scope" — but the nature of their legitimation. (p. 126)
As such, modern [as oppose to postmodern] legitimation has recourse to a universal criterion: Reason. It is this mover that generates what Lyotard famously describes as "metanarratives": appeals to criteria of legitimation that are understood as standing outside any particular language game and thus guarantee "universal" truth (p. 130)
... the biblical narrative and Christian faith do not claim to be legitimated by an appeal to a universal, autonomous Reason, but rather by an appeal to faith (or, to translate, "myth" or "narrative"). (p. 131)
— James K.A, Smith, A Little Story about Metanarratives. In Myron B. Penner, ed., Christianity and the Postmodern Turn: Six Views (Grand Rapid, MI: BrazosPress, 2005)
...in philosophical discourse, "meta" signifies a difference of level and not primarily of size. A metanarrative is a metadiscourse in the sense of being a second-level discourse designed to legitimize one or more first-order discourses (p. 148)
— Merold Westphal, Onto-theology, Metanarrative, Perspectivism, and the Gospel. In Idem.
Is Christianity a metanarrative? Theologians like Kevin Vanhoozer and Michael Horton would suggest not. Rather, Christianity is a "meganarrative" as the the Bible is a grand narrative depicting the historical progression of God and His workings in the world.
The postmodernist Jean-Francois Lyotard famously declared that "I declare postmodern as incredulity toward metanarratives". But what are metanarratives as decried by Lyotard, and is Christianity a legitimate target for incredulity?
In the essay by Smith, metanarratives are distinguished by the fact that they appeal to a "universal criterion of Reason". According to Smith's interpretation of Lyotard, metanarratives are not defined by the scope of their claims but rather the grounds of their legitimacy or authority. Therefore, Christianity according to Smith is not a metanarrative because it is based upon "faith".
In response, one wonders what Smith means by stating that Christianity is based upon "faith". Certainly, if by "universal criterion of Reason" one means a Platonic and Cartesian view of rationality, then Christianity is most definitely not grounded on "Reason". But it is one thing to deny Cartesianism, it is another thing to deny rationality; one does not imply the other.
What exactly is "faith"? Is it a Kierkegaardian existential idea of the "leap of faith"? The problem with throwing around the word "faith" is that one appears pious without actually defining what one means by the term, for after all which Christian is against faith?
In the second quoted statement, Smith seems to equate "faith" with "myth" or "narrative". This is troubling. It brings to mind some of the use of the phrase "mythopoetic language" as it relates to the teachings of Scripture, especially when used by non-literalists to interpret Genesis 1. How does this "faith" or "myth" or "narrative" relate to truth and reality? Is the Christian story intending to set forward universal claims which however is wholly subjective and isolated from reality? Of course, one can embrace a constructivist view of reality, but if so is God then a constructed reality for the needs of Man? It does not help to adopt Merold Westphal's method of inviting others to see and enter into the Christian story (p.234) if Christianity itself is a narrative linguistic construct. What we instead have is the reduction of Christianity to a myth on par with other myths like the Gilgamash Epic. If Christianity is not transcendentally real, the "meganarrative" is mere subjectivism.
It can be argued that the ground of legitimacy is in the evidences for the empty tomb and others like them, in other words Evidentialist Apologetics. By itself however, this does not seem to be protected from Smith's interpretation of Lyotard's criterion of what constitutes "metanarratives". While certainly history is the domain of God's working in the world, empirical data are not self-interpreting. Furthermore, are we to think that the same criterion that Lyotard used against Rationalism is benign against Empiricism, seeing that Lyotard has in mind the entire Modernist enterprise?
If Smith's interpretation of Lyotard in his attack on Modernism is correct, and we mean by "universal criterion" the idea of universal self-evident truths known to Man, then Christianity is not a "metanarrative", but not because it is based upon "faith" (contra Smith). Rather, Christianity is based upon the universally true but externally revealed criterion of revelation, especially in the particularly rationally revealed Word of God. It is not "universally known" but it comes to us extra nos, from outside us. It is also not based upon the naked empirical data of history but the interpretation of the data that comes through God's [General] Revelation described by His Special Revelation.
Smith's interpretative definition of Lyotard's term "metanarrative" seems not to be unanimously held to. Merold Westphal primarily defines "metanarrative" from the sum of its parts, and hence metanarrative is a second level discourse on narratives. Therefore we have metaphysics (discourse on being). metaethics (discourse on being and knowing of ethics), and of course metanarratives, which in his view is discourse to legitimize one or more narratives. According to this modified definition, Christianity must indeed be consider a "metanarrative". To deny that Christianity is not a "metanarrative" in this sense suggest that Christianity is made up of mere stories of which the truth values are irrelevant. So while Christianity as "kerymatic" deals with what it teaches and speaks to the first-level discourse on matters pertaining to church practice and Christian living (p. 239), it has nothing to say about reality. One wonders how Eschatology functions in such a system, since how can Christ be said to come again in the last judgment which is universal and real in scope? Christian eschatology in this system can only function as literary and poetical devices, not as something that will happen again. Ditto for creation too, since both events impinge upon second-level discourses. In fact, the idea of redemptive history is itself a second level discourse, and true fidelity to only usage of first level discourse should logically result in biblical atomism.
So according to Westphal's definition, Christianity is a "metanarrative", notwithstanding his argument against it. To appeal to faith is simplistic for the same reason why Smith is wrong. In fact, the idea that Heilgeschichte (lit. "holy history") is kerygmatic not apologetic is itself a second level discourse statement on the Christian faith (p. 150). That by itself is enough to discount Westphal's attempted synthesis of postmodernism and Christianity.
So in conclusion, is Christianity a metanarrative? Yes and no. In the strict definition of the term, it is indeed one. However, if we adopt Smith's interpretation of Lyotard's definition, then no. Christianity while universal is not universally known but particularly revealed. For our purposes therefore, in apologetics, it would help to know what particular individuals mean by the term "metanarratives" before answering if Christianity is indeed one.