Impurities in understanding of divinity
That is, minor errors, irregularities, or snags. As a whole, the Jewish religious interpretations in exile are correct, but there are some impurities, that is, incorrect treatments of certain aspects of Judaism.
These relatively minor errors and distortions did not particularly cause much harm during the centuries of exile.
That is, achieve national unity on all levels, including the physical (governmental)
And the Judaism that has been brought from exile does not have that highest clarity, as it contains impurities. It therefore cannot serve as the foundation on which to build the State.
This is a paraphrase of the Talmud (Sotah 49b): "In the footsteps of the Messiah insolence will increase." See note to paragraph 2.
Insofar as the renewal of national life requires a relatively clear understanding of the divine, and all impurities impede the advancement of national resurrection, insolence will burn away all that is weak and ugly in the religious sphere. Before the national resurrection, these imperfections did not cause much harm. But now that the resurrection has begun to develop in practice, they have become obstacles, and a "demolition force" will sweep them with insolence from its path.
This is a quotation from the morning prayers. Here, Rav Kook gives it the additional sense that only a new light can shine on the renewed Zion; the old light - the Judaism of exile - is not strong enough.