This certainly is a direct, active opinion statement, and refers to the topic of adult illiteracy in America. However, there are a couple of problems with it as the thesis, or main idea, for the draft you've written.
First, calling adult illiteracy the "greatest threat" to America today is a very large claim: what about all the other terrible problems confronting us? (What a cheerful thought that is!) There's no need to make such a large claim, which may only distract your reader with thoughts of other problems.
Second, the focus of your draft isn't the threat that illiteracy poses--you've got only about one page out of fourteen about how widespread the problem is (maybe for your introduction), and nothing about its consequences (economic, social, political, whatever). Clearly, that's not what your paper is "about." (If it is what you want your paper to be about--or what your reader expects your paper to be about, you've got some major revising to do!) Instead, what your draft does discuss at length are causes and possible solutions, but your thesis doesn't let your reader know that. So, choosing this thesis statement might lead your reader to expect one kind of paper and be disappointed to find a different one (and not appreciate it)!
Please return to the previous page and choose again.