Awhile back I inquired whether there were any reliable statistics of Christian conversions between Orthodoxy, Catholicism, and Protestantism. This was prompted by my wondering if there were many Protestants who had made the move, or instead just a few isolated but well publicized such moves.
Fr. Richard John Neuhaus of First Things, in his Public Square section of the August/September 2008 edition, shares some news of a possible answer (here, subscription required):
"That “U.S. Religious Landscape Survey” issued by the Pew Research Center last February continues to be sliced and diced by various analysts [Thos.: I recently discussed some of its information here], including Robert Benne, who writes in The Cresset, a magazine published by Valparaiso University. “Continuing the list of surprises about Catholicism,” Benne writes, “ten percent of all Protestants are former Catholics but eight percent of Catholics are former Protestants. That eight percent represents a considerable number, around five million. Converts to Catholicism usually are far more intense about their faith than cradle Catholics, so I suspect that this eight percent injects new vigor into the Church.” He also notes that a striking number of Catholic converts are prominent intellectuals. A young man who is active in Catholic ministries at an Ivy League university speaks warmly of their cooperation with evangelical ministries such as Campus Crusade for Christ. Ecumenical cordiality, however, does not preclude an element of evangelistic rivalry. “The big difference,” he says, “is that they aim at the weakest Catholics while we aim at the strongest evangelicals.” The claim is that evangelicals who are more theologically versed and religiously committed are more open to Catholicism, while Catholics who become evangelicals were, for whatever reason, alienated from Christianity. Put differently, religiously serious evangelicals are more likely to become Catholic, while religiously lapsed Catholics are more likely to become evangelicals" (emphasis added).
I, for one, was surprised that the "delta" between conversions to X and conversions to Y was only 2%. It would be interesting to compare fertility rates of these two pools of Christians (and perhaps other factors that a statistically savvy person could hammer out) to make some forecasts if present patterns were to continue. I mean, it is not a given that a +2% in favor of Protestants = long term Protestant growth. I'd still like to know the Orthodox rates, though they are a much smaller pool for statistical purposes.