"Truly, I say to you, among those born of women there has not arisen anyone greater than John the Baptist; yet he who is least in the kingdom of heaven is greater than he...  For all the prophets and the Law prophesied until John."--Jesus (Matthew 11:11 and 13)

"But what did you go out to see?  A prophet?  Yes, I say to you, and one who is more than a prophet.  This is the one about whom it is written, ‘Behold, I send My messenger before Your face, who will prepare Your way before You.’*  I say to you, among those born of women, there is no one greater than John; yet he who is least in the kingdom of God is greater than he."--Jesus (Luke 7:26-28; *Jesus was quoting Malachi 3:1)

17 "Do not think that I came to abolish the Law or the Prophets; I did not come to abolish, but to fulfill. 18 For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass away from the Law, until all is accomplished. 19 Whoever then annuls one of the least of these commandments, and so teaches others, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven."

1 Now there was a man of the Pharisees, named Nicodemus, a ruler of the Jews; 2 this man came to Him by night, and said to Him, “Rabbi, we know that You have come from God as a teacher; for no one can do these signs that You do unless God is with him.” 3 Jesus answered and said to him, “Truly, truly, I say to you, unless one is born again, he cannot see the kingdom of God.” 4 Nicodemus *said to Him, “How can a man be born when he is old? He cannot enter a second time into his mother’s womb and be born, can he?” 5 Jesus answered, “Truly, truly, I say to you, unless one is born of water and the Spirit, he cannot enter into the kingdom of God. 6 “That which is born of the flesh is flesh, and that which is born of the Spirit is spirit. 7 “Do not marvel that I said to you, ‘You must be born again.’ 8 “The wind blows where it wishes and you hear the sound of it, but do not know where it comes from and where it is going; so is everyone who is born of the Spirit.” 9 Nicodemus answered and said to Him, “How can these things be?” 10 Jesus answered and said to him, “Are you the teacher of Israel, and do not understand these things? 11 “Truly, truly, I say to you, we speak that which we know, and bear witness of that which we have seen; and you do not receive our witness. 12 “If I told you earthly things and you do not believe, how shall you believe if I tell you heavenly things? 13 “And no one has ascended into heaven, but He who descended from heaven, even the Son of Man. 14 “And as Moses lifted up the serpent in the wilderness, even so must the Son of Man be lifted up; 15 that whoever believes may in Him have eternal life. 16 “For God so loved the world, that He gave His only begotten Son, that whoever believes in Him should not perish, but have eternal life. 17 “For God did not send the Son into the world to judge the world, but that the world should be saved through Him. 18 “He who believes in Him is not judged; he who does not believe has been judged already, because he has not believed in the name of the only begotten Son of God. 19 “And this is the judgment, that the light is come into the world, and men loved the darkness rather than the light; for their deeds were evil. 20 “For everyone who does evil hates the light, and does not come to the light, lest his deeds should be exposed. 21 “But he who practices the truth comes to the light, that his deeds may be manifested as having been wrought in God.”

Conclusion
A person in God's kingdom who teaches others to annul the least of the commandments in the Law (the first five books of the Old Testament) will be called "least in the kingdom of heaven", yet that person is greater than John the Baptist, who in his lifetime did not have the opportunity to be born of Spirit and enter into God's kingdom, since the Messiah had not yet died for the sins of mankind and risen from the dead.