Bhagavan is one of the names of Vishnu. But Ramanujacharya is referred to respectfully as Bhagavad Ramanuja. Is it all right to use a word that refers to the Lord while talking about Ramanuja? Yes, said P.T. Seshadri in a discourse. There are many reasons why Ramanuja should be called Bhagavad Ramanuja. In his Sri Bhashya, Ramanuja showed us the meaning of Bhagavan, relying on sage Parasara’s explanations. Yamunacharya wanted the world to know of the significance of Pancharatra Agamas, which are referred to as Bhagavad Sastra. Ramanuja wrote a work called Nitya, which is based on the Pancharatra texts. So, he made many aware of what is called Bhagavad Sastra, and hence he is Bhagavad Ramanuja.
The advice that Lord Krishna gave to Arjuna on the battlefield is called Bhagavad Gita, and Ramanuja wrote a bhashya for the Bhagavad Gita. Ramanuja ordered Thirukkurukai Piran Pillan to write a commentary for Nammazhvar’s Thiruvaimozhi. Subsequently more commentaries came to be written by others too. Thiruvaimozhi is called Bhagavad vishaya, and since it was Ramanuja who was instrumental in the writing of the first commentary for Bhagavad Vishaya, he is Bhagavad Ramanuja. Ramanuja made the world realise the greatness of mantras, and this too is a reason for his being referred to as Bhagavad Ramanuja.
Ramanuja was unique, for those associated with him were granted liberation by the Lord. In Nyasa Tilaka, Vedanta Desika says he should be saved because of his connection to Ramanuja. Desika came over two centuries after Ramanuja, but there is an unbroken succession of Acharyas through whom one is connected to Ramanuja. For all these reasons, Acharya Ramanuja should be called Bhagavad Ramanuja.
