Is it permissible to address those named "Abd al-Rahman," "Abd al-Hamid," and "Abd al-Majid" as "Rahman," "Hamid," and "Majid," and what are the Beautiful Names of Allah for which this is forbidden?

If the name added to the word "Abd" (servant of) can be used for other than Allah (such as Hamid (Praiseworthy) and Majid (Glorious)), then there is no harm in calling the person by omitting "Abd" and using only the name (e.g., "O Hamid," "O Majid"), though it is preferable to call him by the full name. However, if the name is specific to Allah Almighty (such as Al-Khaliq (the Creator) and Ar-Rahman (the Most Merciful)), then it is not permissible to call someone named with it by omitting "Abd" (e.g., calling him "O Khaliq" or "O Rahman").