You didn't understand your quote in Jeremiah, did you? Nor do you understand that what Paul preached does not mirror Jer. 31 exactly, but is but a taste of what would come in the end days for the Jews.
If this is what Paul spoke of for his day, why are we given teachers in the church ("they shall teach no more every man his neighbour"), and why are we to preach the Gospel ("they shall all know me")
Jer. 31:31-34 Behold, the days come, saith the Lord, that I will make a new covenant with the house of Israel, and with the house of Judah: 32 Not according to the covenant that I made with their fathers in the day that I took them by the hand to bring them out of the land of Egypt; which my covenant they brake, although I was an husband unto them, saith the Lord: 33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the Lord, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people. 34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the Lord: for they shall all know me, from the least of them unto the greatest of them, saith the Lord: for I will forgive their iniquity, and I will remember their sin no more.
I don't expect you to read much less comprehend the difference, but I'll put it out there for other believers to discuss if they wish. Paul writes about the future kingdom on earth for the Jews, so others will be able to engage.
Romans 11:25-27 For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. 26 And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and shall turn away ungodliness from Jacob: 27 For this is my covenant unto them, when I shall take away their sins.
Check your doctrine, pops. Or, better yet, examine yourself whether you be in the faith.