Can you explain the philosophical concept of the Guru as Brahman and the path of 'undifferentiated worship'?

In Chapter 45, a profound philosophical concept is presented where the Guru is identified as the true Brahman, the eternal reality, while the world is seen as transient. The path to realizing this involves renouncing the transient, which gives rise to dispassion (Vairagya). The seeker is then instructed to meditate only on the Sadguru, who is described as a 'solid mass of Brahman-consciousness.' This constant feeling and meditation eventually lead to a state where divinity is perceived in all beings. This elevated state of perception and worship is what the text refers to as 'undifferentiated worship' (Abheda-bhajan).