Rambam writes (Hil. Yesodei ha-Torah 2:10):
He is the Knower, He is the Subject of Knowledge, and He is the Knowledge itself." All is one.
Now, you could ask the same question on him: since G-d is one, then how can we describe Him by these different terms? Indeed, for this reason Maharal (Gevuros Hashem, 2nd introduction) says that we can't even speak of G-d's knowledge, because He is beyond that or any other description.
R. Schneur Zalman of Liadi points out repeatedly in Tanya (part 1 chs. 2 and 48, part 2 ch. 9, et al) that in fact both perspectives are correct. Hashem Himself is, as Maharal says, completely indescribable; but once G-dliness is "compressed" into the world of Atzilus and the lower worlds, then it is possible to speak of G-d's "knowledge" and of that being one with Him, since it is one of the modes in which He expresses Himself to us created beings.
Torah is G-d's "will and wisdom," and it remains so even in the form in which we study it, in which it largely deals with physical objects (Tanya, part 1, chs. 4-5). The Jewish soul, too, comes from Hashem's attribute of wisdom - anthropomorphically, as a child is engendered from its father's brain (ibid., ch. 2). Thus, both Torah and the Jew are a part of G-d's wisdom - which, as per Rambam's statement, is one with G-d Himself.
(Based on a letter by R. Yosef Yitzchak Schneersohn, originally published in Kitzurim ve-He'aros)