On the other hand, the greatness of Wikipedia hardly needs expounding any more. Yet with Wikipedia (and everything you read) it is still caveat emptor, and sources still need to be checked carefully and critically.
So the other day Barack Obama reportedly told a group of rabbis that he knows more about Judaism than any other president did. This upset a lot of people, most of whom seemed politically motivated, and tried to refute it on a variation of the theme that in times past educated people and religious people were biblically literate (for example). The former presidents were both educated and religious. Therefore they knew their Old Testament, therefore they know more about Judaism than Obama. Now I have no idea whatsoever if Obama knows a little or a lot about Judaism, or how he may have acquired or not acquired this knowledge. Maybe he has a stack of Baron's Social and Religious History of the Jews which he keeps in his bathroom. Maybe he curls up at night with a Daf Yomi edition of the Schottenstein Talmud. Maybe he has read a lot of Heschel. Putting aside the possibility that he too may know his Old Testament just fine, that is simply no indicator of any knowledge about Judaism - not even ancient Judaism, actually. As someone who is deeply interested in Christian Hebraism, who has read a lot of works by Christian Hebraists, I know how to tell when a non-Jew (or Jew) knows a lot about Judaism. The ones who delved into rabbinic literature sometimes did know a lot. The ones who knew their Old Testament probably know a lot about Christianity, but not Judaism.
Charles C. Johnson wrote an article which appeared in Tablet called "Obama’s Historical Chutzpah
Does the president really know more about Judaism than John Adams and James Madison did?" and he ridiculed this notion. Johnson, who is writing a book on Calvin Coolidge, writes: "To make sure that Jewish influence would be felt more widely, [President John] Adams, a polyglot, even translated the Old Testament into English."
Oh? The Old Testament? The Arba Ve-esrim? Can I read this translations? John Adams? Are they still in manuscript? Why haven't I heard of this?
The first thing you have to do when you hear something pretty wild is ask, Is this plausible? The next thing to do is to check. Since I had never heard of this, and since I believe that I would have heard of this if it were true, I decided this must be examined. Why was it that whenever people write about Hebrew in America they talk about Cotton Mather and Ezra Stiles and Urim V'tumim and that Congress contemplated making Hebrew the national language of the United States - another tall tale, as I showed here - don't you think someone might have mentioned that President John Adams translated Tanakh before?
It appears to me that Johnson's source is Wikipedia's section on John Adams in its entry List of Multilingual Presidents which says that "[Adams] also demonstrated proficiency in Hebrew by translating books of the Old Testament into English, and translated parts of the New Testament from Greek." The footnote there gives us a book by Benjamin Franklin (not that one!) published in 2003 called The Other John Adams, 1705-1740. That's right. The other John Adams. By the way, did anyone read or see Coraline? Remember "the other mother?" Spooky. I digress. This other John Adams (henceforth OJA) was not the president, who was born in 1735. OJA was a New England clergyman, and he died when President John Adams was 5.
On pg. 96, Franklin discusses OJA's linguistic proficiency. He shows that Adams had translated Horace from Latin - almost any educated man born in 1705 had to know Latin, at least to read it - and then he writes that "if Adams translated verses from the original languages of the Old and New Testaments - as opposed to reworking English translations of these books - "then he was demonstrably proficient in Hebrew and Greek." Franklin writes this since OJA included some translations from Scripture in his posthumously published book Poems on Several Occasions (Boston 1745), then perhaps he made those translations and perhaps he knew Hebrew well. Franklin then is not sure if OJA made the translations - of verses, not books - himself or only reworked existing translations, but if he did, then it would be a demonstration of his proficiency in Hebrew and Greek. But we have gone far afield, because who cares about Other John Adams? This is still not President Adams.
The end of the matter is, check all sources.
 Note, I have nothing against the implausible. All my years of research, blogging, discussing, etc. have taught me two things. One, the implausible is often very plausible. Two, the implausible is often implausible for a very good reason. I ask myself Is this plausible? and that question leads me on my way.
Edit: I got the chance to look at Other John Adams's Poems on Several Occasions, which you can do for yourself here. The full title contains the subtitle "Original and Translated." His biblical translations include the Songs of Deborah and David - both say they are "paraphras'd," which is an accurate way of acknowledging, I believe, that he made no claim to having translated them. Rather, he rendered his own poetic versions of these songs, but did not in any way translate from the Hebrew. But again, this isn't the president anyway.