Final answer:
Only the third verse of West Germany's national anthem is used because it reflects universal values of unity and freedom, distancing the country from the nationalistic and militaristic past associated with the Nazi regime.
Step-by-step explanation:
Since WWII, only the third verse of West Germany's "The Song of the Germans" has been used in official contexts due to its universal message of unity and freedom, which contrasts with the nationalistic elements of the earlier verses that became heavily associated with the Nazi regime. The first verse, with a refrain talking about Germany above all else, and the second verse, which features territorial claims, were both deemed inappropriate in the context of post-war Germany and its efforts to rebuild and redefine itself.
After WWII, when the decision to use only the third verse was made, the newly established West Germany was emerging from a period of intense de-Nazification and was seeking to establish a democratic state in alignment with the values of the Western allies—United States, Britain, and France—as opposed to the communist East Germany supported by the Soviet Union. As the verses of a national anthem represent national values and ideals, the use of only the third verse symbolized a conscious break from the troubling past and aimed to promote the democratic, peaceful values of the new Federal Republic.