Final answer:
Shastriji Maharaj founded the BAPS Swaminarayan Sanstha and its Upasana in 1907 and established four main principles: Swaminarayan Bhagwan, Akshar/Purushottam Upasana, the importance of Swaminarayan mandirs, and Brahmans as gurus.
Step-by-step explanation:
Shastriji Maharaj established the BAPS Swaminarayan Sanstha and its Upasana in 1907. The four main principles outlined by Shastriji Maharaj are Swaminarayan Bhagwan, Akshar/Purushottam Upasana, Swaminarayan mandir, and Brahmano as Guru. These principles constitute the core beliefs of the BAPS Swaminarayan Sanstha and are central to its philosophy and practices. It advocates the worship of Swaminarayan as God and Gunatitanand Swami as his choicest devotee. It emphasizes the importance of temples as places of worship and the role of enlightened gurus in guiding spiritual aspirants.