The Rabbis have said that the 7 colors of the rainbow represent the 7 Noahide laws, a set of laws that they claim derives from Scripture.

But Scripture actually says the rainbow represents the complete, indivisible Torah of Moses.

Allow me to explain.

First, the number 7 refers to completeness/perfection.  The 7 colors of the rainbow therefore tell us that the rainbow represents the complete/perfect light.

Next, the rainbow is connected with the Shekhinah (Divine Glory):

“And above the firmament that was over their heads was the likeness of a throne, as the appearance of a sapphire stone: and upon the likeness of the throne was the likeness as the appearance of a man above upon it. And I saw as the colour of amber, as the appearance of fire round about within it, from the appearance of his loins even upward, and from the appearance of his loins even downward, I saw as it were the appearance of fire, and it had brightness round about. As the appearance of the bow that is in the cloud in the day of rain, so was the appearance of the brightness round about. This was the appearance of the likeness of the glory of the HaShem. And when I saw it, I fell upon my face, and I heard a voice of one that spake,” Ezekiel 1:26-28

Here we see that the glory of HaShem, which is a perfectly complete light, can manifest as a rainbow with the seven colors representing this perfection and completion.  

Now consider that this complete/perfect, Divine Light of the Shekhinah also shines through the Torah (and through them who study and practice Torah):

“For this command is a fire, this Torah is a light, and correction and instruction are the way to life,” Proverbs 6:23

“And those that understand shall shine as the brightness of the firmament; and those that teach righteousness to the multitude as the stars in perpetual eternity,” Daniel 12:3

“I have more understanding than all my teachers: for thy testimonies are my meditation,” Psalm 119:99

The light of Torah therefore cannot be divided because it represents the light of the Shekhinah–which is G-d Himself:

“The Lord is my light…” Pslam 27:1 

“3. Nahmanides:  Divine Immanence
What is Nahmanides’ understanding of God’s ‘glory’ filling the Tabernacle?  How did he conceive the presence of the shekhinah in the Temple?  Does he necessarily disagree with Saadia and Maimonides?  After all, he does not deny the principle of God’s incorporeality.  From the passages of his introduction to Exodus and his commentary on Exodus 25 cited above, it would seem that he regards the ‘Glory of the Lord’ as something more inherently related to God Himself–and not simply a light that he created.  But this cannot be proven decisively from his words there.
     For clarification, we must turn to Nahmanides’ commentary on Genesis 46, a long passage in which he vociferously attacks Maimonides’ far-reaching abstraction of God’s presence in the physical world–and his reinterpretation of biblical verses that speak in this vein.  In that context Nahmanides states his view regarding Maimonides’ conception of shekhinah quite clearly:
‘Heaven forbid that the matter called shekhinah or ‘glory’ is a created [entity] apart from God Himself, as the Master [Maimonides] has conceived here and in many chapters of his book.’
Speaking quite dramatically, Nahmanides denies the very possibility that the shekhinah or kavod–the ‘Glory of the Lord,’ is something is merely created by God, in other words, anything other than His very essence–as Maimonides had averred consistently.
     Nahmanides marshals proof for his position by citing the Targum of Ezek 3:12, the angels’ praise:  ‘Blessed be the Glory of the Lord from His place'”
‘Jonathan Ben Uziel’s Aramaic said:  ‘Blessed be the Glory of the Lord from the region of His Divine abode’ …If one would say that the verse in Ezekiel refers to a ‘glory’ that was created (kavod nivra’), as is the opinion of the Master with respect to the verse ‘And the Glory of the Lord filled the Tabernacle,’ and other similar verses, then how did the angels direct their words, ‘Blessed, etc.,’ toward it?  For he who blesses and prays to a glory that was created (kavod nivra’) is as he who worshipped idols!
     The teachings of our Rabbis also contain many texts which indicate that the term shekhinah is [i.e., connotes] God, blessed be He.’
As Nahmanides observes, it seems clear enough from Scripture and from the authoritative Targum of Jonathan ben Uziel that ‘the Glory of the Lord’ refers to God Himself–even when it refers to a spatially confined entity,”  “The Temple of Jerusalem:  From Moses to the Messiah” Edited by Steven Fine

“All of the Divine commandments are One, a single unity. This idea finds expression in the verse, “A commandment is like a flame…” – i.e., each commandment is an individual flame. However, the Torah is not the mere sum total of many individual flames; rather, “the Torah is light.” The Torah, which contains all of the individual commandments, is a single unified light. The flames unite to form one great light, for the Torah is a single unit…” Maharal of Prague, Commentary to Pirkei Avot

In conclusion, all Torah-pursuant Messianics should reclaim the rainbow as a symbol of the Glory of HaShem which shines through His perfect Torah.
Shalom,
Peter

Source: Orthodox Messianic Judaism (http://goo.gl/tTgTQM)