References to this subject have tended to emphasise Chesterton's 'guilt' or 'innocence', suggesting that a crime has been committed: he is accused, by inference, of being anti-Semitic before the Holocaust, without further exploration of the implications of this. Furthermore, such 'trials' have frequently overlooked conflicting evidence, and this Jewish Chronicle report of an interview in 1933 illustrates how easy it is for protagonists to situate Chesterton's views on Jews and Judaism at opposite poles.
For example, he asserts that he "still think[s] that there is a Jewish problem" and refers to "'the Jewish Spirit'" as "a spirit foreign to Western countries". However, Chesterton also says he is "appalled by the Hitlerite atrocities" and that Hitler has found "the most famous scapegoat in history" in the Jews; he claims to be ready, along with Hilaire Belloc, to "die defending the last Jew in Europe." Chesterton refers to Hitler wearing the "mark of the barbarian" for being insensible to criticism, and of appealing to force when thwarted; also to Hitler's 'Prussian' "arrogance" displaying the "truculence of the self-righteous" with its implications for "harmless, and in scores of cases, valuable and distinguished Jewish citizens of the German Reich".
There are also phrases suggesting ambivalence, such as references to Hitler's anti-Semitic actions having "no reason or logic behind them" and to the Germans as "a sorely tried people". However, studied in context, these appear to refer to Hitler's "wild promises" to improve the lot of the German people; this interpretation is strengthened by Chesterton going on to say that the "real evils in Germany are still there, more rampant than ever" after describing the German Jews as 'scapegoats' and 'harmless'. This suggests that the evils to which he refers are not Jewish ones.
Nevertheless, his remarks about the 'Jewish problem' and the 'Jewish Spirit' remain to be explored, and the task is too complex to be undertaken in a brief introduction such as this. Chesterton was subject to multiple influences which require careful unravelling in order to come even close to analysing his attitudes to Jews. These influences, which included religion, politics, eugenics and race, and also his friendships with Jews and non-Jews, pose some intriguing questions. For example, how did Chesterton's relationship with Catholicism, as a defender and then as a convert, influence his attitudes? Did early religious influences conflict with later political ones, producing a 'dual image'   of 'the Jew', exemplified by his reverence for religious Jews and 'anti-Semitism' towards secular Jews? Can the trajectory of such attitudes also be traced in Chesterton's reaction to liberalism and its patronising approach to the poor and their concerns, in contrast to his own populism, more redolent of socialism? In the case of his pro-Zionism, this was once assumed to be proof against charges of anti-Semitism  and yet, if his individual stance did not find favour among many Jews, neither was it typical of anti-Semites. Despite his hard-hitting political and economic analysis, Chesterton's gregarious personality led him to make lasting friendships with many Jews; the effects of these, and his relationships with those noted for anti-Semitism (including Hilaire Belloc, and Cecil and Ada Chesterton) can be traced in episodes of his life, such as his schooldays, the Eye Witness years, and the G. K.'s Weekly period.
Last, but not least, there is Chesterton's fiction, an allegorical gold mine where clues to his attitudes to Jews and anti-Semitism are strewn in abundance (although at least one eminent critic has misinterpreted Chesterton's views on 'race' by failing to employ his non-fiction as a key to his fictional treatment of Jews). 
All such territory, crucial to the understanding of this complex philosopher, will be explored in forthcoming editions of the Chesterton Quarterly. Indeed, set in their proper context, Chesterton's attitudes to Jews and Judaism can illuminate other areas of his thinking. It can even - paradoxically - make a positive contribution to the field of contemporary Jewish-Christian relations. As distinguished Jewish commentator Melanie Phillips has noted, Holocaust Remembrance Day is treated with reverence, while anti-Semitic attacks have increased,  suggesting that it is easier to address the anti-Semitism of the past than the anti-Semitism of the present day.
In this context, an important factor that will be noted is the effect of the Holocaust on later commentators' views of Chesterton's 'anti-Semitism'.  Although the Holocaust may be cited by many as the reason for feeling uncomfortable in this connection, it is significant that during and just after the War Chesterton was seen as a prophet of Nazism and totalitarianism,    while fifty years on, one critic compared Chesterton's views of Jewish people to those of Hitler.   This unusual trajectory in Chesterton's reputation is closely linked to increasing interest in the Holocaust; however, it should not blind us to the fact that during Chesterton's life time his 'anti-Semitism' was noted and criticised, especially by Jews - hence the Jewish Chronicle's opening lines: its Editor (and the feeling was reflected in his readership)  classed G. K. with "the most confirmed anti-Semites" and with "bosoms hitherto ... irrevocably hardened against the Hebrew."
However, while one critic's focus on this view of Chesterton suggests the influence of the Holocaust,  the Chronicle's editor chose to headline G. K.'s remarks about Hitler; in fact, he accords them greater worth since they are seen as emanating from an 'anti-Semite'.  While we are fortunate in being able to look back on arguably the darkest period in mankind's history, the Jews at that time had no such luxury; 'history' was still an open book  and many were desperate for recognition of their own view of the dangers of Nazism.
Again, pre-Holocaust, anti-Semitism was not confined to Nazi Germany; there were many degrees of British anti-Semitism, now airbrushed out of history, and the anti-Semitism of many historical figures has been overlooked, leaving individuals such as Chesterton appearing atypical in this respect. However, with the Holocaust at last - and rightly - commanding a high level of interest, Chesterton has been seen increasingly not against the backdrop of anti-Jewish pogroms of the late nineteenth and early twentieth centuries, but against the backdrop of the Holocaust. In fact, he should be studied in the context of the First World War, bearing in mind that, in 1933, Armistice had been declared just 15 years earlier. It was still vivid in men's minds, and was to play a tragic role in the genesis of the Second. Indeed, even statesmen were apparently so absorbed in trying to prevent a 'repetition' of the Great War that they closed their eyes to the dangers posed by the new Dictator, even up until 1939;  with exaggerated atrocity tales from the Great War fresh in people's memories, reports of anti-Jewish activities were dismissed by many. Chesterton never lived to see the Holocaust (if this seems an obvious point, it appears to have been overlooked by some commentators) but it is significant that in 1933 he did see the dangers of Hitler, and recognised that some pacifists were so anxious to avoid war that they were prepared to ignore injustice:

In my experience, most Pacifists do not love their enemies; they only hate their friends for fighting against their enemies. Or rather, properly speaking, the enemies they forgive are really their friends; but they do not forgive those who are really their enemies. The kind of Pacifist who told us for the last ten years to be friendly to Germany would never in ten million years become friendly to France. 

It is also significant that Chesterton did not blame the Jews for their own plight, as English Fascists later blamed them for the War;  instead, he saw the plight of the Jews as an indicator of Hitler's menace. At such a time, and with such a history, it is understandable that Jews would be alert to injustice against Jews - but an anti-Semite? That was certainly worth a headline.

References:

English pantomime features comic interaction between the actors and the audience including vigorous disputation.
  For example, Canovan, M., G. K. Chesterton: Radical Populist, New York, 1977, p.136.
  The religiously-influenced idea of the dual image of the Jew in literature could excite horror, fear, hatred but also wonder, awe, and love. (Fisch, H., The Dual Image: A Study of the figure of the Jew in English Literature, London, 1959, p.11) This was seen as stemming from Christian views of a deicide nation which nevertheless could also potentially redeem mankind (ibid, p.270).
  Whitehorn, K., 'The Return of G. K. Chesterton', 1974, in Conlon (Ed.), G. K. Chesterton: A Half Century of Views, Oxford, 1987, pp.305-309. However, Kaufman (1998, op cit) argues that Chesterton's pro-Zionism stemmed from a wish to get rid of Jews.
  Cheyette, B., Constructions of the Jew in English Literature and Society: Racial Representations 1875 - 1945, Cambridge, 1995.
  'Phillips: [Holocaust Memorial Day] is "extremely sick"', Jewish Chronicle, 4.3.2005, p.7; 'Cardinal condemns rise of anti-semitism in UK', Catholic Times, 20.2.2005, p.3.
  Brown, I., 'A Multiple Man', 1944, in Conlon, op cit, pp.57-58.
  Kaufman, G., 'Chesterton's final solution', Times Educational Supplement, 2.1.1998.
  The Rev. Morris Joseph, letter to the Jewish Chronicle, 23.6.1911, p.14.
  Rapp, D., 'The Jewish Response to G. K. Chesterton's Antisemitism, 1911-1933', 1990, in Patterns of Prejudice, vol.24, nos. 2-4, pp.75-86.
  See Stone, Stone, D., Responses to Nazism in Britain, 1933-1939: Before the War and the Holocaust, Basingstoke, Hants., 2003.
  Neville Chamberlain's attempts at appeasement were set at nought by Hitler's aggression; the ageing Liberal politician Lloyd George visited Hitler in Munich in 1936, one of many specially invited British guests. (Griffiths, R., Fellow Travellers of the Right: British Enthusiasts for Nazi Germany 1933-9, London, 1980, pp.222-223).
  'The Pacifist as Prussianist', The End of the Armistice, 1940, p.207.
  Lebzelter, G., Political Anti-Semitism in England 1918-1939, London, 1978, p.46.