Will we embrace the material principle of the Gospel without embracing the formal principle of Sola Scriptura?
During the Reformation, the material principle was the principle of Justification by Faith alone, while the formal principle was Scripture Alone or Sola Scriptura. In an interaction on a blog I have had with some New Calvinists , there has been the insistence that Gospel-centeredness is enough, for Gospel-centeredness will necessarily preclude what I call Gospel-Onlyness — the view that everything is decided with respects to its impact on and consequence of the Gospel. Does embrace of the material principle therefore necessarily implies the embrace of the formal principle? Why then does the Reformation consists of two principles instead of merely one, and the insistence on the supreme authority of the Scripture for all of life as much as the Gospel itself was the issue of contention?
The formal principle of Sola Scriptura deals with the epistemological foundation of the faith within which the Gospel will thrive. Without the foundation, there are no set boundaries on what the Gospel actually is limited to. This does not mean of course that the Gospel does not have implications on various sundry issues, but the fact of the matters is without an epistemological foundation, upon what authority can agreement on the major issues be made, and what basis can defence be made against sophisticated denials of the Gospel which professes to be Gospel-centered like for example New Perspectivism? Even within the current movement, is being Gospel-centered really sufficient? Prof. D.A. Carson is part of The Gospel Coalition, an organization that is supposed to be Gospel-centered and supports Sola Scriptura in its confessional statements , yet he is also for the usage of gender-inclusive Bibles, which has a practical impact on the doctrine of Sola Scriptura by making such "Bibles" less literal and more importantly, conveying less of God's truth thus practically undermining the authority of the Scriptures in the lives of those who use such "Bibles" . So is it really true that embracing the material principle, of being Gospel-centered, will necessarily cause the full embrace of the formal principle of Sola Scriptura? The case of D.A. Carson certainly does not seem to prove so. While it is true that emphasizing belief in Sola Scriptura does not necessarily preclude anyone from denying it in word or action, at least Scripture can function as a safeguard within which all matters of life and doctrine can be settled, instead of an authoritative appeal to the Gospel without its corresponding epistemic foundation.
 Gospel-centered or Gospel-only?, dated January 17, 2009 (http://ephesians310.wordpress.com/2009/01/17/gospel-centred-or-gospel-only/), and Gospel-centered or Gospel-only? A brief response, dated February 2, 2009 (http://ephesians310.wordpress.com/2009/02/02/gospel-centredor-gospel-only-a-brief-response/)
 "Revelation", Confessional Statement, The Gospel Coalition Network (http://www.thegospelcoalition.org/about/foundationdocuments/confessional)
 D.A. Carson, The Inclusive-Language Debate: A Plea for Realism (Grand Rapids, MI, USA: Baker, 1998)
 Vern Poythress and Wayne Grudem, The Gender Neutral Bible Controversy, Updated Edition (Ross-shire, Scotland, UK: Christian Focus Publications, 2003)