On the upcoming holiday of Tisha b’Av, which begins this evening, Jews mourn not only the destruction of the First and Second Temples but all instances of persecution throughout the ages. Thus, one of the liturgical poems traditionally recited by Ashkenazim commemorates the burning of the Talmud by church authorities in Paris in 1242. Lawrence Schiffman explains why medieval churchmen came to view the Talmud with such hostility:
The earliest person to polemicize against the Talmud directly was probably Petrus Alphonsi, a Jewish physician and scholar who converted to Christianity in 1106 and was formerly known as Moses Sephardi. . . . The first sections of his Dialogue against the Jews attacks Judaism to a great extent by challenging the Talmud and the ancient rabbis. Whereas previous claims had been that the Jews continued to practice biblical law [while] refusing to accept Christianity, Petrus now claimed that the Jews were following what he said was a new and false law—that of the Talmud.
Somewhat different was Peter the Venerable, the Benedictine Abbot of Cluny (ca. 1092-1156). [Although] hostile to Jews and Judaism, he [nonetheless] wanted to see Jews spared from violence. . . . Peter composed a lengthy polemic against the Jews that included an attack on the Talmud. Peter [was] the first [influential author to make] an attack of this nature, although those who followed him had much more thorough familiarity with the [text itself, at a time] when European Christendom was crystallizing a new spirited opposition to Jews and Judaism. . . .
By the 13th century, Jewish converts to Christianity began to provide much greater [access to] talmudic learning to increasingly anti-talmudic Christian authorities. The first of these converts was Nicholas Donin, who lived in the first half of the 13th century. He argued that the Talmud was intolerable to Christians and that Christian society should destroy it. He set in motion the process that would lead to the burning of the Talmud in France in the 1240s.
Read more on Lawrence Schiffman: http://lawrenceschiffman.com/when-the-talmud-was-burned/