There are some controversies that never die down.
Whether Tamil is more ancient than Sanskrit,Caste is foisted on the people by the Brahmins, Babri Masjid was not built-in Ram’s Birth place, Taj Mahal was not built by Shah Jahan,Aurangzeb is a pious Man and the list is endless in India.
One such controversy is that the Balaji Temple was originally Lord Murga’s Temple and it was later converted into a Vishnu Temple.
Tirupati is Murugan Temple.
1.Most common proof is the fact that the ancient Grammar of Tamils, right from Tholkappiyam while defining the characteristics of land masses, assigns Hilly terrains as the Abode of Lord Muruga.(Thinai Illakkanam).
Land Masses were divided into five categories by the Tamils.
Kurinji-Hilly Terrains,-Deity Lord Muruga
Marutham- Agricultural Land-Indra
Neydal-Coastal Regions-Lord Varuna.
I do not find any reason either from the Purnas or Tamil Literature to support the view that it was Muruga’s Temple.
The term Vengadam means the northern boundary.(of Tamils)
And there is no evidence of any King having built a Muruga Temple.
The Purana Accounts are legendary and is not helpful in finding the probable date of the temple. Puranas concentrate how Vishnu came voluntarily to take his place there. Varaha temple at the foothills of Tirupati predates venkateshwara temple at the top. The only account relavant here is Tondaman (pallava) started the worship of vishnu here. This Thondaman assisted his brother(Akasa Raja) in administration. Thondaiman had a foster daughter in Tirupati and she was married to venkatesa. After the death of Akasa Raja (left a young prince), he and his nephew fought and tondiaman felt very weak ,so got the weapons from venkateswara . The war ended Indecisively and the country was divided into two. The one closer to Vengadam (Tirupati) was given to thondaman and the other farther away given to his nephew. Tondaiman built the temple and started the festivals. This Tondaman lived in Kaliyuga. There is a separate Thondaiman dynasty post 12th century AD. But Dravidian scholars want to identify Thondaiman as Pallava.’
However there is another argument that it has been a Shiva Temple because , even to-day Vilvarchana is being done to Lord Balaji.
Kanchi Periyavar states that in the Temple Prahara(outside wall, there are images of Lions, which are associated with only Goddess Durga and the temple could have been a Durga Temple.
There is another confusing statement from Romila Thapar.
My view is that there is no evidence that Tirupati is a Muruga Temple.
It is Lord Vishnu‘s Temple.
I would say this to die-hard Saivite.
Lord Muruga is the favorite nephew of Lord Vishnu.Lord Muruga will be pleased if you worship His favorite Uncle.
மாமனுக்கோ பிள்ளை இல்லை மருமகன்தான் தலைமகன்-Kannadasan.
The Uncle has no children, his nephew is his eldest son.