Thanks for your nice comments. My Brother in Islam. Of course, they are about Islam. Islami Davet (Islamic Invitation) recites good nasheed about nothing but Islam. And, i'm sure you'll understand the lyrics. Because origins of most Turkish words are Arabic and Persian. There are only 3 thousand words left in our old Turkish. So, you'll get the meaning, at least guess what it is about.
Because every Muslim knows Islamic Terms (in Arabic).
here check one; http://www.islamidavet.com/dinle/dinle/5/index.html
la ilahe illallah means (There is no God but Allah)
Ayasofya (Hagia Sophia; one of the oldest mosques in Istanbul. Now a museum!! it is about this tragedy)
Rahmetel-lil-Alemin (Mercy for the Worlds; a nasheed about our Blessed Prophet) ... etc..
i think anyone who listens to them will understand. if not, again it is good to listen to Islamic Music