I want to name my newborn Shihāb Ad-Deen. What is your opinion?

I see no objection to the name Shihāb Ad-Deen. However, there are names better than this that include servitude to Allah, and they are better. Allah’s Messenger (salallāhu ʿalaihi wasallam) said: “The most beloved names to Allah, the Most High, are Abdullāh and Abdur-Rahmān.” (Abu Dawood 4949, Ibn Mājah 2833 and others). If you name him Abdullāh or Abdur-Rahmān, Abdul-Kareem, Abdul-Malik, or Abdul-Qādir, or something similar among the names that display servitude to Allah, the Most Perfect, then that is better and more virtuous.

See See Fatāwā Noor ʿalad-Darb of Imām Ibn Bāz, 18/234.