John Chrysostom

"And as Esaias said before, Except the Lord of Sabaoth had left us a seed, we had been as Sodoma, and had been made like unto Gomorrha." Here again he shows another thing, that not even those few were saved from their own resources. For they too would have perished, and met with Sodom's fate, that is, they would have had to undergo utter destruction (for they of Sodom were also destroyed root and branch, and left not even the slightest remnant of themselves,) and they too, he means, would have been like these, unless God had used …

Homily on Romans 16 ↗

Theophylact of Ohrid

Having said that the remnant will be saved, he now explains what this means, and says that God left us a chosen seed and bread, for the word "left" he used instead of "chose," so that if God had not preserved it, we would have been subjected to destruction, like the Sodomites and Gomorrahites, as those condemned for their sins.

Commentary on Romans ↗

Thomas Aquinas

Then, when he says and as Isaiah foretold, he cites the texts pertaining specifically to the apostles, saying: and as Isaiah foretold: unless the Lord of the Sabbaoth, that is, of armies or power, had left us, namely, in his mercy, a seed, i.e., the word of the Gospel: the seed is the word of God (Luke 8:11); or a seed, i.e., Christ; and to your seed which is Christ (Gal 3:16); or a seed, i.e., the apostles: that which shall stand therein shall be a holy seed (Isa 6:13), we would have fared like Sodom and been made like Gomorrah. …

Commentary on Romans ↗