The words קְּדֹשִים תִהְּיוּ symbolises the Kesser of ‘Ze’eir Anpin’ and the words כִי קָּדוֹש אֲנִי symbolises the Kesser of Aarich (as is mentioned earlier).
And yet even the very highest of levels כִי קָּדוֹש אֲנִי is also extended to Yisroel and as mentioned earlier that even the third crown is also extended to Yisroel since it came into being as a result of their Avodah.
This also explains why when the Possuk states קָּדוֹש קָּדוֹש קָּדוֹש ה׳ צְּבָּאוֹת "Holy, holy, holy is HaShem the Lord of Hosts” the Possuk concludes מְּלֹא כָּל הָּאָּרֶץ כְּבוֹדוֹ “The whole earth is full of His glory”. This is because since the three times repetition of the word Kodosh is connected with the Avodah of humans in the lower realm therefore is it present in כָּל הָּאָּרֶץ in the entire earth, except that the holiness and the third crown is concealed right now and will come into a revealed state in the future with the coming of Moshiach as mentioned earlier: “In the future, the righteous will have Kodosh – “Holy”, recited before them, as it is recited before HaKodosh Boruch Hu.”
