Religious Freedom and International Law
In 1990 the IARF held its 27th Congress at Hamburg, Germany on the theme, "Religions Cooperating for One World." Hans Küng delivered the opening address, and the end of the Cold War in Europe was much on the minds of participants. The General Assembly passed a number of resolutions concerning religious freedom that affirmed international law, the process of democratization in Romania, and increased advocacy by the IARF on behalf of religious freedom.

The General Assembly also passed a resolution on the purposes and inclusiveness of the IARF that identified: "The need to broaden the IARF's membership to include all the world's major religious groups." A tour after the Congress took participants to Romania to visit Unitarian churches in Transylvania.

Diether Gehrmann retired at this Congress, and Robert Traer began his service as general secretary.