The following translation of the Epistle of Barnabas ix,4-9 is from the Loeb Classical Library Series, Apostolic Fathers I, translated by Kirsopp Lake, Harvard University Press in Cambridge Massachusetts, and William Heinemann Ltd in London, 1970 reprint, p. 371,373.

“4. But moreover the circumcision in which they trusted has been abolished. For he (the Lord) declared that circumcision was not of the flesh, but they erred because an evil angel was misleading them.

5. He says to them, “Thus saith the Lord your God” (here I find a commandment), “Sow not among thorns, be circumcised to your Lord.” And what does he say? “Circumcise the hardness of your heart and stiffen not your neck.” Take it again: “Behold, saith the Lord, all the heathen are uncircumcised in the foreskin, but this people is uncircumcised in heart.”

6. But you will say, surely the people has received circumcision as a seal? Yes, but every Syrian and Arab and all priests of the idols have been circumcised; are then these also within their covenant? — Indeed even the Egyptians belong to the circumcision.

7. Learn fully then, children of love, concerning all things, for Abraham, who first circumcised, did so looking forward in the spirit to Jesus, and had received the doctrine of three letters.

8. For it says, “And Abraham circumcised from his household eighteen men and three hundred.” What then was the knowledge that was given to him? Notice that he first mentions the eighteen, and after a pause the three hundred. The eighteen is I (= ten) and H (= 8) — you have Jesus —and because the cross was destined to have grace in the T he says “and three hundred.” So he indicates Jesus in the two letters and the cross in the other.

9. He knows this who placed the gift of his teaching in our hearts. No one has heard a more excellent lesson from me, but I know that you are worthy.”

Without removal of the prepuce or foreskin there can be no circumcision of the heart. It is utterly impossible! The author of the epistle has argued his case emotively with no understanding whatsoever of circumcision.