If one recalls the time frame from which Radio Replies emerged, it can explain some of the frankness and lack of tact in the nature of the responses provided.
It was during this timeframe that a considerable amount of anti-Catholic rhetoric came to the forefront, particularly in this country. Much of this developed during the Presidential campaign of Al Smith in 1928, but had its roots in the publication of Alexander Hislop's The Two Babylons, originally published in book form in 1919 and also published in pamphlet form in 1853.
While in Britain (and consequently Australia), the other fellow would surely have experienced the effects of the Popery Act, the Act of Settlement, the Disenfranchising Act, the Ecclesiastical Titles Act, and many others since the reformation (that basically boiled down to saying, "We won't kill you if you just be good, quiet little Catholics"). Even the so-called Catholic Relief Acts (1778, 1791, 1829, 1851, 1871) still had huge barriers placed in the way.
And of course, they'd both remember the American Protective Association, "Guy Fawkes Days" (which included burning the Pontiff in effigy), the positions of the Whigs and Ultra-Torries, and so on.
A strong degree of "in your face" from people in the position of authoritativeness was required back in the 1930s, as there was a large contingent of the populations of both the US and the British Empire who were not at all shy about being "in your face" toward Catholics in the first place (in other words, a particularly contentious day on Free Republic would be considered a mild day in some circles back then). Sure, in polite, educated circles, contention was avoided (thus the little ditty about it not being polite to discuss religion in public, along with sex and politics), but it would be naive to assume that we all got along, or anything resembling that, back in the day.
Having said all of the above, reading the articles from the modern mindset and without the historical context that I tried to briefly summarize above, they make challenging reading, due to their bluntness.
The reader should also keep in mind that the official teaching of the Church takes a completely different tone, best summed up in the Catechism of the Catholic Church:
817 In fact, "in this one and only Church of God from its very beginnings there arose certain rifts, which the Apostle strongly censures as damnable. But in subsequent centuries much more serious dissensions appeared and large communities became separated from full communion with the Catholic Church - for which, often enough, men of both sides were to blame."269 The ruptures that wound the unity of Christ's Body - here we must distinguish heresy, apostasy, and schism270 - do not occur without human sin:Where there are sins, there are also divisions, schisms, heresies, and disputes. Where there is virtue, however, there also are harmony and unity, from which arise the one heart and one soul of all believers.271
818 "However, one cannot charge with the sin of the separation those who at present are born into these communities [that resulted from such separation] and in them are brought up in the faith of Christ, and the Catholic Church accepts them with respect and affection as brothers .... All who have been justified by faith in Baptism are incorporated into Christ; they therefore have a right to be called Christians, and with good reason are accepted as brothers in the Lord by the children of the Catholic Church."272
819 "Furthermore, many elements of sanctification and of truth"273 are found outside the visible confines of the Catholic Church: "the written Word of God; the life of grace; faith, hope, and charity, with the other interior gifts of the Holy Spirit, as well as visible elements."274 Christ's Spirit uses these Churches and ecclesial communities as means of salvation, whose power derives from the fullness of grace and truth that Christ has entrusted to the Catholic Church. All these blessings come from Christ and lead to him,275 and are in themselves calls to "Catholic unity."276
838 "The Church knows that she is joined in many ways to the baptized who are honored by the name of Christian, but do not profess the Catholic faith in its entirety or have not preserved unity or communion under the successor of Peter."322 Those "who believe in Christ and have been properly baptized are put in a certain, although imperfect, communion with the Catholic Church."323 With the Orthodox Churches, this communion is so profound "that it lacks little to attain the fullness that would permit a common celebration of the Lord's Eucharist."324
269 UR 3 § 1.
270 Cf. CIC, can. 751.
271 Origen, Hom. in Ezech. 9,1:PG 13,732.
272 UR 3 § 1.
273 LG 8 § 2.
274 UR 3 § 2; cf. LG 15.
275 Cf. UR 3.
276 Cf. LG 8.
322 LG 15.
323 UR 3.
324 Paul VI, Discourse, December 14, 1975; cf. UR 13-18.
Radio Replies Volume Two: Proof of God's Existence
Radio Replies Volume Two: God's Nature
Radio Replies Volume Two: Supreme Control Over All Things and the Problem of Suffering and Evil
Radio Replies Volume Two: Destiny of Man/Death
Radio Replies Volume Two: Immortality of Man's Soul & Pre-existence Denied
Radio Replies Volume Two: The Human Free Will
Radio Replies Volume Two: Determinism Absurd
Radio Replies Volume Two: Necessity of Religion
Radio Replies Volume Two: Salvation of the Soul
Radio Replies Volume Two: Voice of Science
Radio Replies Volume Two: Religious Racketeers
Radio Replies Volume Two: Divine Revelation
Radio Replies Volume Two: Revealed Mysteries
Radio Replies Volume Two: Existence of Miracles
Radio Replies Volume Two: Gospels Historical
Radio Replies Volume Two: Missing Books of the Bible
Radio Replies Volume Two: The Bible Inspired
Radio Replies Volume Two: Biblical Account of Creation
Radio Replies Volume Two: New Testament Problems
Radio Replies Volume Two: Supposed Contradictions in Sacred Scripture
Radio Replies Volume Two: Source of Christian Teaching
Radio Replies Volume Two: Jewish Rejecton of Christ
Radio Replies Volume Two: Christianity a New Religion
Radio Replies Volume Two: Rational Foundation for Belief
Radio Replies Volume Two: Causes of Unbelief
Radio Replies Volume Two: Divisions Amongst Christians
Radio Replies Volume Two: Schisms Unjustified
Radio Replies Volume Two: Facing the Problem