What this strange book is about, at least in part.  Macguffins: baptism and murder.  And Free Indirect Discourse, natch.  The Protestant vs. the Catholic bible.  O'Connor quoting from Douay-Rheims.  The relevant passage in Matthew:

[7]And when they went their way, Jesus began to say to the multitudes concerning John: What went you out into the desert to see? a reed shaken with the wind? [8] But what went you out to see? a man clothed in soft garments? Behold they that are clothed in soft garments, are in the houses of kings. [9] But what went you out to see? a prophet? yea I tell you, and more than a prophet. [10] For this is he of whom it is written: Behold I send my angel before thy face, who shall prepare thy way before thee. [11] Amen I say to you, there hath not risen among them that are born of women a greater than John the Baptist: yet he that is the lesser in the kingdom of heaven is greater than he. [12] And from the days of John the Baptist until now, the kingdom of heaven suffereth violence, and the violent bear it away. [13] For all the prophets and the law prophesied until John: [14] And if you will receive it, he is Elias that is to come. [15] He that hath ears to hear, let him hear. [16] But whereunto shall I esteem this generation to be like? It is like to children sitting in the market place. [17] Who crying to their companions say: We have piped to you, and you have not danced: we have lamented, and you have not mourned. [18] For John came neither eating nor drinking; and they say: He hath a devil. [19] The Son of man came eating and drinking, and they say: Behold a man that is a glutton and a wine drinker, a friend of publicans and sinners. And wisdom is justified by her children. [20] Then began he to upbraid the cities wherein were done the most of his miracles, for that they had not done penance.

Matthew, 11: 7-20, in the Douay Rheims Bible