Can you explain the philosophical concept of the Guru as Brahman and its link to 'undifferentiated worship'?

The teachings present a profound spiritual concept by equating the Guru with the ultimate reality. Chapter 45 explains that Brahman is eternal while the world is transient, and the Guru alone is the true Brahman. By renouncing the transient world, a seeker develops dispassion, or 'Vairagya'. The Sadguru is described as a 'solid mass of Brahman-consciousness.' Meditating solely on the Guru with this understanding is the means to achieve the spiritual goal. This advanced practice ultimately leads to a state where divinity is perceived in all beings, which is termed 'undifferentiated worship' or 'Abheda-bhajan,' transcending the physical form to recognize the Guru's essence in all of creation.