Maier was very involved in the resistance against the National Socialists. As early as May and June 1940, he contacted resistance groups around Jakob Kaiser, Felix Hurdes, Lois Weinberger, Adolf Schärf and Karl Seitz. Out of his conviction, the Catholic faith and Austrian patriotism, he was a resistance fighter, who ultimately did not rule out militant means to suppress the Nazi regime. He founded the resistance group Maier-Messner-Caldonazzi together with the Tyrolean Catholic-monarchist resistance fighter Walter Caldonazzi, who already led a resistance group in Tyrol with the policeman Andreas Hofer and Franz Josef Messner, the general director of the Semperit works. It was Maier who brought the very different members of the resistance group together and was able to build on a large network of his contacts. This Catholic Conservative group is called "perhaps the most spectacular single group of the Austrian resistance." The aim of the group was to bring about an end to the horrific regime by military defeat as soon as possible and to re-establish a free and democratic Austria.