2 But when He went on to say, “But now they have no excuse for their sin,” some may be moved to inquire whether those to whom Christ neither came nor spoke, have an excuse for their sin. For if they have not, why is it said here that these had none, on the very ground that He did come and speak to them? And if they have, have they it to the extent of thereby being barred from punishment, or of receiving it in a milder degree? To these inquiries, with the Lord's help and to the best of my capacity, I reply, that such have an excuse, not for every one of their sins, but for this sin of not believing on Christ, inasmuch as He came not and spoke not to them. But it is not in the number of such that those are to be included, to whom He came in the persons of His disciples, and to whom He spoke by them, as He also does at present; for by His Church He has come, and by His Church He speaks to the Gentiles. For to this are to be referred the words that He spoke, “He that receives you, receives me;” and, “He that despises you, despises me.” “Or would ye,” says the Apostle Paul, “have a proof of Him that speaks in me, namely Christ.”
Source: Tractates on the Gospel of John (New Advent)