Nagaraja Chapter 2 Part 6

I hate to be that guy, and I know this is a bit late... but the 'Batara Guru' and 'Bathala' are not related expressions of the same original being and are not linked. The scholars who identified the two have no objective justification to imply this.

The root word of 'Bhatarra' is a sanskrit influenced word on South East Asian languages that means lord. And because the Indians influenced much of the SEA culture sphere of the aboriginal austronesians, it is plausible and not surprising to see that two distant groups of malay people (Tagalogs and Javanese) who are united by influence of the same culture (Hindus) lingually will call their chief god 'Bhattara' or 'Lord' newly attained influenced word in their language like so.

Bathala is a Native Tagalog god, but he has native aboriginal names (not sanskrit influenced) is either Maykapal (Powerful/Creator), Lumikha (Creator) or May Ari (Owner/Lord) or sometimes even comined! Bathala Maykapal. Sometimes he was even called by another Sanskrit god title "Diwata" which is derived from Devata which is derived from Deva, related to the words Indo European Deus, Deity or Theoi from Greek since Sanskrit is an Indo-European langauge. Beside that, Bathala has next to no hindu or indian influence.

Batara Guru's nature is much more Hindu in nature, though in his name is also Sanskrit, Guru is an epithet of some Hindu god. And he is sometimes identified with the Hindu God Shiva, and the motif some versions of him throughout Indonesia is that he is part of a Hindu like Trinity. Batara Guru's expression in the culture he's found in appears to be almost entirely under the operative expression of an Indonesian HINDU God, synthesis of Hinduism and Indonesian culture. In fact, Batara Guru is arguably a direct Hindu God himself, one that is expressed in Indonesian culture. That is why he is even seen as just an Indonesian expression of Hindu Gods like Shiva or even an Avatar.

THIS is not the nature of Bathala. The nature of Bathala is despite his sanskrit name, he operates entirely like a totally simplistically viewed aborinal folk god as opposed to a God of Hinduism or organized religious dogma, the only link he has to Hinduism is his name that is not even always applied to him in fact. Like some Animistic Filipino high ranking deities, He is too distant to be even worshiped and too great to be approached or bothered by mere humans. Graven images of him are non existent, and he is seen somewhat like a deistic legend deity, that is still to be highly respected and revered. Bathala is not even portrayed in any art in ancient culture still. And has 0 in common with Guru other than the name, he is not even part of a dogmatic structural group like a Trinity. He instead just sends Anitos to intervene on his behalf to deal with mortal affairs. Bathala is also often seen as eternal, not subservient or inferior to no God.

Bathala Maykapal, the Tagalog CHief God has much much more root in common personality and nature wise with the other neighboring ethnic group's chief gods like Kaptan, Gugurang, Lumawing, Kabunian, Tunkung Langit and etc. and do not have a Batara title attached to them. a lot of these deities are supreme in their respective cultures (Bikol, Bisaya, Ifugao, etc.) somewhat distant, folk and etc. Bathala has more link with them than he does with Guru.

The two gods are viewed TOTALLY differently in their respective cultures, and operate TOTALLY differently as respective religious figures, one is more Hindu and the other is more Aboriginal Malay, if not entirely Malay and have totally different personalities and religious expressive nature and have indications they have different root. The only thing that binds them is that their worshipers were influenced by Sanskrit. This is totally obvious, since the native gods of all Malay cultures that separate Tagalogs and the Indonesians don't even call any of their chief gods as Bathala.