An interesting misuse of Msgr. Ronald Knox.
Knox was a British playwright and theologian-priest who died in 1957. (The plot Orson Welles’ “War of the Worlds” may have come from H.G. Wells, but the execution came from Knox’s “Broadcasting from the Barricades.”) He quite certainly did not make that quote in response to the Catholic Charismatic Movement.
Speaking in unknown tongues is certainly a diagnostic symptom for demonic possession, but that doesn’t mean it’s singularly indicative of possession. I’m sure Knox wouldn’t say St. Francis Xavier, St. Gregory Nazienzen, Pope John Paul II or St. Irenaeus were demon-possessed.
The 1917 Catholic Encyclopedia is much abused around these parts; Where the encyclopedia records the predominant opinions of (protestant-dominated) 1917 America, Protestants here use it as if the Catholic Church itself has conceded points to Protestants. But I think anyone would find its article on glossolalia still quite relevant nearly 100 years later: http://www.newadvent.org/cathen/14776c.htm
What our dog thought about Ronald Knox ... zzzzzzz ....