Arnold Harding was born in 1887 as the son of Berta (Bertha) Winterstein and David Abeles from Bohemia. He was a Czechoslovakian citizen. He had a brother Paul, born in 1882, from his mother's first marriage. After David Abeles died in 1897, Berta Abeles married his brother Philipp, and Arnold had a half-brother Alfred from this marriage. In 1912 Arnold changed his surname to Harding and left the Jewish community. His brothers also changed their name to Harding. Until the annexation of Austria to the German Reich, Arnold Harding lived in his parents' house at Mittelgasse 27 in Vienna's 6th district. He was a partner in Galerie Harding, founded in 1928 and trading in antiques and pictures with a focus on export business.

After the annexation, the Harding brothers were persecuted by the Nazi regime on account of their Jewish origins. In May 1938, the employee Helene Silverio, who was already engaged to Arnold Harding, took over the share of the half-brother Alfred Harding, who had fled to the Czechoslovakia. In December 1938 Arnold Harding applied to the Property Transaction Office to sell the company to Helene Silverio. The approval issued in January 1939 referred only to the premises and furnishings. Arnold Harding, who was still a Czechoslovakian citizen, was given permission to give the pictures to Silverio for sale on commission. He states that he was summoned repeatedly to the Gestapo and the Central Office for Jewish Emigration. His efforts to emigrate were unsuccessful. At the same time he was subject to massive pressure from the art dealer Eduard Nierscher, who had worked in the gallery until 1935 and was now attempting through blackmail to acquire title to the gallery – albeit without success. Arnold Harding was able to avoid deportation by going into hiding from November 1941 to April 1945 in Silverio's apartment at Weihburggasse 4 in Vienna's 1st district. In January 1942 Harding was registered by the police as "departed to an unknown destination". During the time in hiding he was unable to leave the apartment or shelter in the basement during air raids.

Arnold Harding and Helene Silverio married a few days after the end of the war in May 1945. Arnold Harding no longer applied for reissue of the trade licence that had been taken from him in 1939, but the gallery continued to operate with Helene Harding as sole proprietor until she relinquished the trade licence in 1974. In 1949 it was officially renamed Galerie Helene Harding. It was not until the 1960s that Harding received compensation for the persecution, life in hiding and loss of revenue and recognition as a victim. The fate of his brother Paul, who fled to France in 1938, is unknown. His half-brother Alfred was deported from Prague to Majdanek in 1942 and murdered there.