Ever since the Franks under Chlodwig settled in the Neckar region around 500 the area has been predominantly Christian and when Heilbronn was first mentioned in an official document in 741 Christian Michaelsbasilica, present day's Kilianskirche, was mentioned along with the city. The Teutonic Knights constructed its church from the 13th century and both churches were continually expanded. They were joined later by other churches and cloisters in the city.
Around 1050 an important Jewish community was mentioned that had settled in what became known as the Judengasse (Lohtorstra�e). In 1298, 143 Jews were killed during the Rintfleisch-Pogrom and in 1350 Jews suffered attacks again during a European epidemic of the Bubonic plague. The city's constitution required the council to include Jews, but already in the middle of the 15th century Jews were the target of vigilantes again until they were evicted from the city in 1490 with the blessings of Emperor Frederick III.
It is worth noting that the common Jewish name Halpern, and many variants such as Alpert, derive from the name of this city Heilbronn, and the early Jewish community there.
While Heilbronn was part of the Diocese of W�rzburg, the independent villages of B�ckingen, Neckargartach and Frankenbach were attached to the Diocese of Worms. From 1514 on the Heilbronn native Johann Lachmann was caretaker of the parish in St. Kilian, in 1521 he became its preacher, in 1524 he converted to Lutheranism and proceeded to teach and lead the Reformation in Heilbronn against the wishes of both dioceses. After the Protestant reformation of Heilbronn was complete the city remained Lutheran for centuries and the council and citizens accepted the Augsburg Confession without dissent. Catholics were no longer welcome, Jews were prohibited from settling in Heilbronn, and the city took part in the Protestation at Speyer on April 19, 1529 (the Protestation was the origin of the terms Protestant and
