A letter hand-written by the great Reformer Martin Luther which shows the antisemitism that characterised him in his later years is being auctioned by Boston-based RR Auction.

Luther, whose act in nailing his 95 Theses attacking Catholic doctrines to the door of the Castle Church in Wittenberg is held to have started the Reformation, was in favour of dialogue with Jews earlier in his life. However, by 1543, when he wrote this letter, he had become bitterly hostile to them.

The letter was written to Georg Buchholzer, Provost of St Nikolai in Berlin, about a dispute the latter had with Pastor Johann Agricola from Eisleben, known as Magister Eisleben, who was tolerant towards Jews. Luther's letter contains a furious diatribe against Agricola, of whom he says that 'he will give up his life before he gives up his lying'. He says Buchholzer is right to preach against Jews, who he says are 'devils incarnate' who 'curse our Lord' and 'abuse his mother as a whore'. He adds that 'anyone who is capable of eating or drinking or associating with such a foul mouth is a Christian as well as the devil is a saint'.

The letter was only discovered in 1914, in the collection of Baron Heinrich von Hymmen (1880-1960). The Hymmen family supported the Confessing Church that resisted the Nazis during the Second World War and Heinrich placed his castle at Unterbach at its disposal.

The letter is expected to fetch more than $300,000.