Of course, our attention will fall, naturally, on the Gospel lesson, the tale of the Prodigal Son. But in doing so, there is no reason on earth that we might not cite one of Donn'e own reflections upon the same text. And Father A. is here to help.
In Sermon LXXXVII, undated but preached at a christening, Donne deals principally with Galatians 3:27, and the idea that is baptism we "put on" or "are clothed with" Christ. It is in this context that he draws our attention to Luke 15:22, in which the gracious father calls for a long robe -- "the best one" -- to clothe his son:
When the prodigal child returned to his father, his father clothed him entirely, and all at once. He put a robe upon him, to cover all his defects -- which robe, when God puts upon us, in clothing us with Christ, that robe is not only as Augustine says, but it is as Ambrose enlarges it. It does not only make us as well, as we were in Adam, but it enables us better, to preserve that state; it does not only cover us, that is, make us excusable, for our past, and present sins, but it indues us with grace, and wisdom to keep that robe still, and never to return to our former foulnesses, and deformities. (Alford ed., punctuation altered).The quotations are from (1) Augustine's Quaestionum Evangeliorum Libri Duo, 2:33, "the first robe is the dignity which was lost by Adam," and (2) Ambrose's De Cain et Abel, 1:6:24, "the putting on [a garment] of wisdom and piety."
Please note, preaching companions, that Donne himself is not by any means a type of the Prodigal Son. Although it took him quite a while to discern his vocation, he was a lifelong and extraordinarily devout Christian. From a family of passionate (and sometimes martyred) Roman Catholics, he wrestled mightily with the question of conformity to the established church. But even as a law student and aspiring courtier, he spent his leisure time composing theological tractates both speculative (Biathanatos) and polemical (Ignatius His Conclave).
In other words, we beg you not to be deceived by Donne's own self-bifurcation, and to be overly sharp in distinguishing "Jack Donne" from "Dean Donne." They were the same man, with the same life-long interests.