"Kedoshim Tihyu"- What does it mean to be kadosh?

In Parshat Kedoshim, we are commanded to be kadosh, holy. But what does "kadosh" really mean? What exactly are we being commanded to do?

Rashi says that "kedoshim tih'yu" means to be separated from sin; he specificaly says the sin of "arayot." Ramban writes that this commandment is a general statement going back on the previous parshah which specified different things that are forbidden to us; arayot, lashon harah... When the Torah tells us to be kadosh, it means prishut even from that which is allowed. Technically, one can be a "naval b'reshut haTorah." As long as one drinks kosher wine and eats kosher meat, he can drink all the alchohol he wants and be a glutton. By being kadosh in this way, by limiting yourself from even that which is permitted, you then better cling to Hashem and be closer to Him. Sforno explains that we need to be careful from overindulging in all these worldly things in order to attempt to be more like Hashem. We are, after all, created B'Tzelem Elokim.

Rav Shimon Shkop writes in the hakdama to his sefer, Shaarei Yosher, a different meaning of kedushah and what it means to be "kadosh" as commanded in Parshat Kedoshim. Hashem created us b'tzelem Elokim, with the same structure as His, kivyachol. Hashem also created everything in order to do good for it. It is His will that we follow in that path to be good to others. Hashem puts life into us so that we can make ourselves kadosh by using all our physical and spiritual strength to do good for the many people that there are; according to our own ability. This is the idea of "Kedoshim tih'yu", writes Rav Shkop. This mitzvah inludes within it the very root of our purpose. All our actions and work should holy, in that they are for the good of entire group of Bnei Yisrael. When a person really strives to do this, to have all his actions intended towards to the good of the larger froup of Bnei Yisrael, then even those things which he does for himslef, to keep his body healthy is part of this mitzvah, becasue through this he can continue to do more good for others. But when a person takes in worldy pleasures excessively, that is against the spirit of kedushah because he is acting only for his own good and not for the good of others: and there is no purpose for that. Just like Hashem created everything, and every moment he uphold the world all He does is kodesh in that they are for the good of all creation, so too everything we do should be holy and intended towards the good of other people, not just ourselves. After all, the mesdrash says that you might have thought you could reach the highest level of kedushah like Hashem, kivyachol, were it not for the 2nd part of the pasuk- "ki Kadosh Ani Hashem." Whatever kedushah is, it must be something which pertains to both Hashem and us. Prishut has no relevance to Hashem, so how could I have thought that one can reach the level of Hashem in that way? Rather it is in the sense of sleflessness and doing good for others that we emulate Hashem.

(see Shaarei Yosher for more details)

Chiddushei HaLev- Kedoshim

"Kedoshim tihyu ki Kadosh Ani HASHEM Elokeichem" (19:2)

The medrash in Vayikra Rabbah expounds that once the pasuk said "kedoshim tihyu" you might have thought that you could reach the level of Hashem, kivyachol. So "ki Kadosh Ani" comes to teach us that the kedushah of Hashem is greater than than our kedushah- "Kedushati l'maala m'kedushatchem."

Here we see that were it not for this 2nd part of the pasuk, Bnei Yisrael would have thought we could attain the highest level of kedushah. We need a pasuk to tell us that only HB"H is on that highest level of kedushah.

Chazal teach in the medrash (B"R); R' Hosheiya said that when Hashem created Adam HaRishon, the Malachai HaSharet erred and wanted to say "kadosh" before him. Seemingly, before Adam sinned, he was on the highest level of kedushah to the point where the Malachai HaSharet wanted to say "kadosh" before him. They couldn't discern between HB"H and Adam HaRishon, kivyachol.

Pertaining to this, the Alter of Slabodka, R' Nosson Tzi Finkel zt"l, taught a fundamental concept: That even after Adam sinned with the Etz HaDaat and fell from his high madrega, the ability was always within him to rise back to his greatness. Similarly, we find that by Kabalat HaTorah, Bnei Yisrael returned back to they great and holy level of Adam HaRishon before his chet.

Ramchal writes in Mesilat Yesharim, someone who is kadosh - "nechshav k'mishkan k'mikdash u'k'mizbeach." - he is considered like a mishkan, mikdash, and a mizbeach. The food & drink of such a person are elevated to the extent that it is if they were really brought on the mizbeach.
The level that a person can reach is so great. Rambam writes (Hilchot T'shuva 5:2) that every person has the ability to be a tzaddik like Moshe Rabbeinu (Meaning: we can each reach our own personal highest level just as Moshe did). We have within our essence the power and ability to attain the loftiest heights of kedushah!

Every person has to realize the essence of his greatness, that we are created B'Tzelem Elokim, as well as his power and ability, to be a tzaddik like Moshe Rabbeinu. This realization will arouse within a person to not let his life and abilities to go to simply become hevel va’reik. Chazal teach (Tanna d’Bei Eliyahu) that every person has ask himself, “when will my deeds reach the level of the deeds of the avot; Avraham, Yitzchak, and Yaakov?”

Rabbeinu Yonah writes in sefer Shaarei HaAvodah, the first thing that a person needs to realize is his own level, and to recognize of the greatness of his ancestors; their gadlus and importance, as well as their closeness to Hashem. And once someone realizes this, he needs to constantly attempt to strengthen himself and to raise himself to this level. One needs to act in a way in which he will not bring shame to his ancestors and their ways and actions! When someone has a desire rise within him the chutzpah to do something that is not proper, he should ashamed for bring shame upon himself and upon his avot! He should tell his nefesh: “How can some as great and important as me, who has many good qualities, ben gedolim u’ben malchei kedem!- a son of great men and of kings of old, do such an evil thing. How can I sin to Hashem and to my avot?!” As explained by Rabbeinu Yonah, knowing one’s own level is the 1^st fundamental thing a person needs to realize in order to distance himself from aveirot and to strengthen himself towards mitzvot. This concept is more influential than any other divrei mussar. Even more than contemplation (hisbonenut) for Yirat Hashem, omek hadin, or hefsed mitzvah k’neged scharah u’schar aveirah k’neged hefsedah!