Personally, I do not think it is important to profess that the writings of the New Testament were written by those to whom they are ascribed. This issue is especially relevant in discussing the Pauline corpus, with scholars debating Pauline authorship of many of the letters (Van Voorst 417). With a strong majority of scholars denying Pauline authorship of Ephesians, 1 & 2 Timothy, and Titus (Van Voorst 417), readers of these books are left to decide between the knowledge of modern biblical scholarship and the words on the page of the biblical text. While this is an important decision, I do not think it is a decision between faithfulness and unfaithfulness to the message and intention of the text; rather, the choice to profess the findings of biblical scholarship, that Paul himself likely did not write all of the letters in the Pauline corpus, is a choice to respect both the words on the page as well as modern knowledge. This is the case because biblical scholarship doubts Pauline authorship precisely because of the words on the pages of these letters. For example, one of the reasons why scholars believe that Colossians was not written by Paul is because the language used in the letter portrays followers of Christ as already raised with Christ, standing in contrast to the traditional Pauline concept of believers being in the process of being saved, as illustrated in the undisputed Pauline letter to the Romans (Brenneman 3/30/11). Thus, while it may seem like scholars are going against the words on the pages of these letters that ascribe them to Paul, by pointing out the likelihood of pseudonymity, they are actually being faithful to the words and message of the letter as a whole.
It seems to me that the issue of truth stands at the core of this question. I imagine that many of the difficulties people have with accepting the fact that Paul did not write all of the letters ascribed to him are related to beliefs in the inerrancy of the Bible. I can certainly understand concerns that if one sentence of the Bible is not true, how can the rest of its message be trusted? However, these concerns are related to a very literal reading of Scripture, and in that case, there are much larger issues than Pauline authorship (i.e. the historical accuracy of the exodus and conquest). Even the history books of the Bible are theological and cannot be read as historical or scientific facts. The Pauline corpus is no different; as readers, we must understand the original context and original intent of the author, whether or not that author was Paul. Further, we must understand the practice of pseudonymity in the ancient Near East; when we read pseudonymous Pauline letters, we must keep in mind that the author of the letter meant to honor Paul with the words. Thus, acknowledging that Pauline authorship of the disputed letters is not a literal truth is not dishonoring the truth of the text, but honoring the truth as well as the author’s intentions.