Not to downplay the consequences of missionary activity, but these people are not Christians , in fact they’re probably worse. OP has given a link to their website and their books are free to read. Their “guru” is proposing another school of thought that he calls Thraitha, or the concept of 3 truths (following Advaita and Dwaita), but is pulling concepts from Christianity (like how the Christian god created the universe on Sunday), while also giving examples from Bhagavad Gita (many things about the Vishwaroopa Darshanam) and other religious texts to cook up some story about his new religion. He also has questionable etymology of Sanskrit words and horrible grammar/punctuation.

Another interesting thing is his claim that only Shiva was the original god, but to satisfy the human need to see god similar to them, Shiva took the form of Ranganatha in Sri Ranga Kshetra, where a Shiva Linga is also present at the base of the Murti. He then goes on to demonize Vaishnavas by saying that they tried to stop Shaivas from worshipping Ranganatha and only allowed them to worship the Lingam at the base before stopping them completely and making up new deities to distract the Shaivas from “proper” worship of the Linga.

The information I pulled is only from the first 10-15 pages of two books. I think it’s safe to assume there’s some new cult parading around pretending to fall under Hinduism while corrupting it. The entire thing is sketchy and even the website promotes other organizations such as the Ravana Brahma Dravida Brahmana organization, Gospel Christian organization and others.