Complex sentence: There are no idols, statues, or religious pictures in a gurdwara, but the essential feature of a gurdwara is the presiding presence of the holy book and the eternal Sikh Guru, the Guru Granth Sahib.
Split into simpler sentences: There are no idols, statues, or religious pictures in a gurdwara. The essential feature of a gurdwara is the presence of the holy book and the eternal Sikh Guru, the Guru Granth Sahib.