All I know is that in Hinduism, Sanat Kumara was one of the four sons of Lord Brahma who took instruction under Lord Shiva to spread Dharma (Righteousness) across India/The World. This is why Hinduism is synonymous with the term Sanatan Dharma.
https://en.wikipedia.org/wiki/Four_Kumaras
Anyway, try as hard as he could, every attempt Lord Brahma made to get progeny he created from his mind to actually breed, failed...until Lord Vishnu stepped in.
The story about Sanat being one of the Nordic ET's is news to me...I always thought he was created somewhere in India...possibly Shambala at the dawn of time and is one of the 9 Ascended Masters according to the Book of Enoch...but what would I know?
There's a hell of a lot of history between the dawn of time and now.
That being said:
Refer to the Seventh Prapāṭhaka of the Chāndogyopaniṣad - it explains it all.
As for Jesus and Lucifer? no idea.