Symptomatic
Some very good comments to the "Asymptomatic" post below, reminding me that I was speaking with the academic version of the "royal we." I don't think that the English enthusiasm for Charlotte Yonge has quite crossed over to the United States, but it's true that there are a number of niche markets for nineteenth-century Christian fiction. Inheritance Publications and Lamplighter Publishing, for example, both reprint quite a few Anglo-American Victorian novels, although the selection in both cases seems a little random (a lot of Mrs. O. F. Walton; Susan Warner; Elizabeth Prentiss; a surprising amount of E. D. E. N. Southworth; several novels about the Huguenots; the occasional A. L. O. E., Deborah Alcock, and Emma Leslie). Moreover, a bit of noodling about on the 'net turns up a number of novels--by George Sargent, for example, or E. H. Walshe--reprinted on Christian websites or by churches. Presumably, the rise of Google Books will make such novels far easier to acquire (that is, if the libraries doing the scanning would kindly refrain from limiting access to snippet view).
What's difficult to ascertain, as Arnold Hunt points out, is whether or not such books have been read consistently since they were published, or have been recently rediscovered. Moreover, if they were recently rediscovered, how were they found? If the book only went through one edition, did children read it in a Sunday School library--or did it just cease to exist? Many of these books were not bound to last (RTS and Shaw publications have a bad habit of crumbling if you look at them sideways), so it's always tempting to wonder if a book survived the decades because nobody bothered reading it. All sorts of difficult questions here.