Tanya Chapter 46 part 4. Could you imagine that Hashem calls Himself by your name?

Now we explore the second meaning of "kideshanu" in the blessing for mitzvot. Hashem has literally made us holy with His intrinsic holiness, which is completely beyond the worlds. He becomes your G-d, His Essence manifesting through you, when you carry out a mitzvah, and thus we are obligated to stand up for someone who is fulfilling a mitzvah, even if they are ignorant and a boor.  In the act of a mitzvah, you become a chariot for the Divine just like Patriarchs. The only difference is, that their bodies were refined, so they felt it, and the rest of us are beset with the darkness of the body which obscures the incredible fusion that we experience.