Another reviewer, in 2002, commented on this film: "The film unfortunately ends rather abruptly and arbitrarily. Matathias has only got as far as the Middle Ages when the curse is suddenly lifted and he is permitted to die. No compelling reason is given for why this particular time and place should be the end of the Wandering Jew's journey." In fact, the Middle Ages segment is the second one; it is followed by the Renaissance segment and finally the Spanish Inquisition, in which the Jew is burned as a heretic. I think the answer to the decision to end the Jew's life in this period has to do with the period when the film was made, the early 30s, when the Nazis were once again asking "Are you a Jew?" and condemning people based on the answer.
(I should add that the same director made a silent film of The Wandering Jew, 10 years earlier, and there is a note on IMDb that his star was famous in the role in theatrical productions. So the story and probably its blazing finale were established in a stage version much earlier.)
The original story would be that the Jew is to wait "until Christ comes again," i.e. the Second Coming, the Last Judgement. The film script modifies this to "until I come to you again," and the plot shows us the slow progress of Mathatias from a man who would rather see his beloved dead than alive with her husband, to an understanding of the Christian hope in life after death and a less selfish love (in the Italian story, where he decides not to kill his wife as a gesture of possession when she wants to become a nun), to an actual Christ-like role in the Seville sequence, where a whore defines her relationship with him as that of Mary Magdalene to Christ (thank heavens the DaVinci Code theory had not been cooked up at the time). So Christ "comes to him again" as he is being burned as a heretic.
Interestingly, his heresy consists of (1) blasphemy, in saying that Christ might be hard put to recognize his own, i.e. the inquisitors themselves, since they are not Christlike, and (2) refusing to deny his Jewishness. Christ, of course, was himself brought before the High Priests on a charge of blasphemy. The film sort of finesses the problem of baptism (in the version I saw, there was no evidence of the Italian son's being baptized, but the friar says that he has gone to Heaven when he dies), which is what the Inquisitors are in principle asking Mathatias to undertake.
However, the decision is presented to him not as being baptized in Christ but rather as denying his Jewishness, ceasing to be a Jew, and in the early 30s the ringing declaration--by a Christ figure--"I am a Jew!" must have been pretty strong stuff.
The end of another British film starring Veidt, Jew Suss, is similar; Suss in fact has a choice to declare himself not Jewish, since in fact his father was a local aristocrat, but he opts to die a Jew, representing the people he grew up with. Both Suss and Mathatias are heavy-duty sinners (lust, avarice, and pride to say the least) and their Jewishness is not "normalized"--parts of the Wandering Jew look like an excellent production of Merchant of Venice--but they redeem their sins by their concern for the poor, the outcast, and, in Jew Suss's case, specifically Jews in a pogrom situation.
Since Veidt in fact insisted on declaring he was a Jew on official German forms in the early 30s, although he wasn't (his wife was), his choice of two roles of Jewish martyrs was a pretty obvious political move. (Later in Hollywood he starred as a Nazi general in Escape, whose plot turns on the internment in a prison camp of a famous American Jewish actress who was born in Germany.) I think there was a lot of denial in the UK and America about the situation of the Jews under the Nazis, and Veidt seems to have done what he could to make it clearer that antisemitism should disgust decent people and especially Christians.
