Morality will not stand without its source
The infinite divine light by itself is perfect; however, in order for it to appear to us in this world it must be "rectified" accordingly, and this "rectification" occurs by means of the manifestation of the universes, as only in such universes (and with their aid) are we able to apprehend it. In other words, somewhat paradoxically, by means of the creation of universes the infinite divine light is advanced, developed, and improved (rectified) - not in relation to itself (which is unnecessary, as it is already perfect), but in relation to us, in that we now, with the help of the universes, can apprehend it. This remarkably radical theological idea is one aspect of Rav Kook's mysticism - his vision of the unity of creation, which views this world as an integral part of eternity, and the temporal as necessary for the realization and manifestation of eternity, rather than as superfluous to it or impeding it.
In other words, morality and ethics do not merely spring from a connection with God; they cannot continue to exist without that connection. If the link is broken, morality will begin to wither. An individual person may be quite ethical and moral without connection to God. However, if a secular concept of morality destroys the connection (and morality begins to be based on such ideas as "evident standards of decency," "live and let live," or Kant's Categorical Imperative), then within the framework of society ethics will gradually lose their life force, fade and wilt, and finally become unstable and disintegrate - just as trees, when it ceases to rain, do not immediately wither but remain green for a time and, at a glance, may appear to be thriving without rain, but cannot last long this way. For more detail see also Poetry of Being by Yosef ben Shlomo, Chapter 8, "The Profane Spirit and the Ethics of Holiness."
Since the divine is boundless, it cannot be fully expressed in any one tradition. Therefore, it must be expressed in various forms and must take on a different character with each nation or group. Accordingly, other non-Jewish forms of religious tradition are far from mere "mistakes" or misunderstandings of God on the part of other peoples. The existence of these other traditions is important, as our own Jewish tradition, being realized and formalized, is inevitably limited in comparison with the boundless divine. This radical religious pluralism is an essential element of Rav Kook's theology.
That is, the unity that runs through the various religious and spiritual models must overcome all differences, as "God will be one and His Name will be one" (Zechariah 14:9). In other words, Rav Kook's religious pluralism is more than simply an acknowledgment that that there are many acceptable approaches. In the future manifestation of unity ("must necessarily vanquish") all of this variety will not be an array of differences, but one unified picture.
Concluding notes: Three main ideas can be distinguished in this paragraph:
1. (a fairly ordinary idea that has been repeated by other writers): that morality will wither if it is severed from its divine source
2. (fairly radical): that the infinite light is rectified by means of the manifestation of the universes.
3. (extremely radical): that any limited, formalized conception is incomplete and, therefore, that religious pluralism is a necessity
The second and third ideas spring from Rav Kook's vision of the parts of the universe as an integral part of the positive manifestation of God.