In "A Modest Proposal" how does Swift use irony to satirize anti-Catholic feelings?

Jonathan Swift's satirical pamphlet “A Modest Proposal” is a purely ironic attempt to offer a solution to Ireland's hunger and overpopulation problems in the early 18th century. While most of the essay is spent outlining his argument that Irish infants should be sold and eaten at one-year of age, there are two instances in which the speaker, who is not Swift himself (since Swift is being satirical and does not really believe what he is writing), directly addresses Catholics.

Swift's motivation was the prejudice of the Protestants in Ireland and England toward the Irish Catholics. Over time, the Catholic population in Ireland had become more and more persecuted, as they were denied employment and fundamental rights, including the right to vote. Although Swift was not a Roman Catholic, he was concerned about their plight.

The following excerpt is the first mention of Catholics in the essay:

. . . there are more children born in Roman Catholick countries about nine months after Lent, the markets will be more glutted than usual, because the number of Popish infants, is at least three to one in this kingdom, and therefore it will have one other collateral advantage, by lessening the number of Papists among us.

The irony here is emphasized by the matter-of-fact tone the speaker uses, as though the idea of eating Catholic infants is indisputably right and just.

A little further on in the essay, the speaker says:

For first, as I have already observed, it would greatly lessen the number of Papists, with whom we are yearly over-run, being the principal breeders of the nation, as well as our most dangerous enemies, and who stay at home on purpose with a design to deliver the kingdom to the Pretender, hoping to take their advantage by the absence of so many good Protestants, who have chosen rather to leave their country, than stay at home and pay tithes against their conscience to an episcopal curate.

This paragraph makes reference to the political situation in England and Ireland in the early 18th century. There is irony in the fact that the speaker makes it sound like the Protestants are the ones being persecuted, rather than the Catholics, which was not the case.