A reader who arrives at the Guru Granth Sahib expecting either a defence or a rejection of ritual will find neither, and the pattern is consistent enough across the rag sections to be worth stating on its own.
The volume treats existing observance as a real thing pointing in a real direction and then declines to stop where the observance stops. Pilgrimage is met with the observation that the pilgrimage that matters is interior. Ritual bathing is met with the question of what is actually being washed. The sacred thread is met with a description of a thread made of compassion and contentment that cannot break or be soiled. The fast, the sacred site, the ashes of the ascetic and the fine distinctions of caste purity are each handled the same way.
Two things follow that are easy to get wrong. The first is that this is not iconoclasm; the compositions do not read as attacks, and their tone is more often patient than scornful. The second is that it did not produce a religion without practice. Sikh observance is substantial and specific, and much of it grew directly from these compositions being sung at the occasions they address.
What the volume declines is the transaction. It does not accept that an act performed correctly obliges any outcome, and the target of its criticism is nearly always the person conducting the observance as a claim rather than the observance itself.