That’s easy. Academic scholars.
They’re the contemporary experts who study the subject using the historiographic, textual, and archeological methods that have been developed since the Enlightenment.
Bart Ehrman (for example) is a far more reliable guide to what the individual gospel writers were trying to say than either Billy Graham or Joseph Smith. Not because Ehrman is an agnostic, but because he has participated in high level debate on the subject in academic journals and conferences.
His opinion about who Jesus was carries far more weight (or ought to) than, say, suburban-dwelling Protestants and Mormons, arguing at their door steps on a Saturday morning, about this or that passage in the Bible.
Indeed, it’s precisely Christian and Mormon “interestedness” in Jesus that ought to make their judgments about him all the more suspect. By contrast, a biblical scholar, whatever his or her faith tradition (or lack thereof), relies on evidence and reason to draw, in argument with other scholars, conservative, as opposed to fanciful, conclusions.
Scholarship rewards cautious judgment, which makes for fewer errors.
Furthermore, the average religious believer—and that includes the meat-and-potato clergy—has the atrocious habit of conflating biblical authorship (“the Bible says this” or “the Bible says that”). The Bible actually doesn’t say anything. Individual authors of individual texts say things. And they have individual purposes (personal, rhetorical, theological) that may be at cross-purposes with others—including the other authors who made it into the Bible.
Traditions, sects, and cults downplay attention to the individual authorship of biblical texts because then they would have to admit that the texts don’t speak with one voice—their voice.
By contrast, academic scholars have actually studied the primary documents and data surrounding the individual authors in question and have argued about what the individual authors were up to. In this sense, the assertions of the religiously committed concerning “who Jesus was” fog our understanding of the early Jesus tradition (by making, say, Mark “fit” with John, and vice versa).
So, when it comes to the Bible, let’s name things for what they are. With respect to the conflation of the biblical authors favored by, say, traditional Christian believers, here’s the truth: it’s an appealing and imaginative associative interpretation that binds everything up in a tidy package. But there’s no good reason to think that the package’s relation to, say, the Jesus of history is anything more than a mirage.
I chose the above song, by the way, because it’s actually an old spiritual from the American black church. The contemporary evangelicals singing it changed the words to smooth out a biblical reference glitch. The original lyric (toward the beginning of the song) is the following:
In my God’s Bible, in the Book of James, Christ was a-healin’ the crippled and the lame.
The songwriter clearly needed a rhyme (or, at least, a near-rhyme) for “lame” and chose “James” (even though the story appears in Matthew). In the above, the error has been replaced with a conflation—“the Word proclaims.”
It’s still a great song.
Here’s the original: