26 “The hour comes, and now is, when the true worshippers shall worship the Father in spirit and in truth. We worship that which we know: ye worship ye know not what; for salvation is of the Jews.” A great thing has He attributed to the Jews; but do not understand Him to mean those spurious Jews. Understand that wall to which another is joined, that they may be joined together, resting on the corner-stone, which is Christ. For there is one wall from the Jews, another from the Gentiles; these walls are far apart, only until they are united in the Corner. Now the aliens were strangers and foreigners from the covenants of God. According to this, it is said, “We worship what we know.” It is said, indeed, in the person of the Jews, but not of all Jews, not of reprobate Jews, but of such as were the apostles, as were the prophets, as were all those saints who sold all their goods, and laid the price of their goods at the apostles' feet. “For God has not rejected His people which He foreknew.”
Source: Tractates on the Gospel of John (New Advent)