"ואנשי קודש תהיון לי ובשר בשדה טרפה לא תאכלו .../You shall be a holy people for me; do not eat flesh of an animal mauled to death in the field …" (Shmos 20:23) The pasuk teaches that we become holy people when we follow the dietary laws.
According to the holy Rav Menachem Mendel of Kotzk z"l, this pasuk is teaching us something fundamental about being holy. From this pasuk we learn that God gave us the ability to be holy and made retaining holiness dependent upon our actions.
The Sfas Emes elaborates. God does not lack holy beings. The spiritual realms are full of angels, seraphs and holy spiritual creatures. Still, God specifically wants our holiness. But we are physical beings living in a physical world. How is it possible to be holy while living in the physical world? The answer is that it would not be possible if God had not imbued us and the world around us with holiness, with spirituality, albeit in measured doses. Everything in the world contains holiness commensurate with its task. Our job is to align our physical selves and actions with the holiness that is within us. We must make sure that our actions are appropriate for our holiness.
We can infer this from an interpretation that Chazal[1] give the second half of this pasuk. Removing a sacrifice from the Beis HaMikdash invalidates it. Chazal learn this halacha from our pasuk. They interpret the pasuk, "Meat (a sacrifice) that is in the field (outside of its boundaries since a field is unbounded) is like an animal that has been mauled to death, do not eat it." Being outside the Beis HaMikdash is inappropriate for the holiness inherent in the sacrifice. The Sfas Emes understands this as a principle that applies to life in general.
We can also understand the beginning of the pasuk as promise. God is telling us that ultimately He will become revealed and we will be dedicated to Him. The word for holy in Hebrew also connotes dedicated. Therefore we must watch ourselves now so that we will be prepared when that time comes.
A Midrash teaches the same idea through an allegory. The Midrash relates of a man who is decorating a crown with gems and pearls. A passerby encourages him since the crown will ultimately adorn the head of the king. We too, will ultimately be totally dedicated to God so it is imperative that we prepare ourselves now.
According to this understanding, "ואנשי קודש תהיון לי .../And you will be a holy people to me …" fits well with a deeper understanding of קודש/holy as explained by the Rishonim. ["ואתם תהיו לי ממלכת כהנים וגוי קדוש .../And you will be for me a priestly kingdom and a holy people." (Shmos 19:6) According to the Ramban and Rabbeinu Bechaye[2], "גוי קדוש/a holy people, is better translated as "a people of the Holy One." Here to, "אנשי קודש/holy people" could be translated as "people of the Holy One."[3]]
God's promise to us is that we will ultimately be connected to Him in a way that we cannot even fathom now. It is our responsibility to prepare ourselves now for that day, acting in ways that are in alignment with the holiness that is within us.
[3] The Sfas Emes does not clarify to which Rishonim and which sod he is referring. I believe he is referring to this idea mentioned by the Ramban and Rabbeinu Bechaye and possibly others as well.