Irenaeus Against Heresies 4.31.2
2 Thus, after their simplicity and innocence, did these daughters [of Lot] so speak, imagining that all mankind had perished, even as the Sodomites had done, and that the anger of God had come down upon the whole earth. Wherefore also they are to be held excusable, since they supposed that they only, along with their father, were left for the preservation of the human race; and for this reason it was that they deceived their father. Moreover, by the words they used this fact was pointed out — that there is no other one who can confer upon the elder and younger church the [power of] giving birth to children, besides our Father. Now the father of the human race is the Word of God, as Moses points out when he says, Is not He your father who has obtained you [by generation], and formed you, and created you? At what time, then, did He pour out upon the human race the life-giving seed — that is, the Spirit of the remission of sins, through means of whom we are quickened? Was it not then, when He was eating with men, and drinking wine upon the earth? For it is said, The Son of man came eating and drinking; and when He had lain down, He fell asleep, and took repose. As He does Himself say in David, I slept, and took repose. And because He used thus to act while He dwelt and lived among us, He says again, And my sleep became sweet unto me. Now this whole matter was indicated through Lot, that the seed of the Father of all — that is, of the Spirit of God, by whom all things were made — was commingled and united with flesh — that is, with His own workmanship; by which commixture and unity the two synagogues— that is, the two churches — produced from their own father living sons to the living God.
Genesis Rabbah 51
AggadahHis wife looked behind her—Rabbi Isaac said, for she sinned with salt. That night when the angels came to Lot, what was she doing? Going to all her neighbors and saying to them, ‘Give me salt, because we have guests.’ And her intention was that the men of the city would come to know of them. Therefore “she became a pillar of salt.” And the older one said to the younger, ‘Our father is old, etc.’ (Genesis 19:31). They believed that the world had been destroyed, like in the time of the flood. (Genesis 19:32) ‘Come, let us make our father drink wine, etc.’ Rabbi Tanchuma in the name of Rabbi Shmuel [said]: (Genesis 19:32) ‘Let us preserve offspring through our father.’ It does not say ‘a son from our father,’ but rather ‘offspring from our father.’ That offspring that comes from another place. And who is this? This is the Messiah. (Genesis 19:33) She made her father drink wine, etc.
Notes and References
"... Lot's incestuous union with his daughters seemed to provide obvious grounds for condemning him ... It is interesting, however, that some interpreters seized upon a detail in the biblical text to defend the daughters' actions. For when the daughters resolve to do this deed, it is because the older says to the younger, 'Our father is old, and there is not a man on earth to come to us after the manner of all the earth' (Genesis 19:31). Now, in context, this seems to mean merely that Lot's daughters, dwelling alone in an isolated mountain cave with their father (Genesis 19:30), had no one ('not a man on earth') to turn to for a mate. But perhaps the expression 'not a man on earth' meant more ..."
Kugel, James L. The Bible as it Was (pp. 193-194) Harvard University Press, 1998