Jhn 17:17 Sanctify them through thy truth: thy word is truth.
Separate them in reality; your law is what is real.
The word translated as "sanctify" here is first seen in the Gospels as "hallowed by thy name" from the Lord's pray. The Greek word used is hagiazo, a verb from the adjective hagios, meaning that which creates awe or more simply, an awful thing. Hagiazo generally means "devoted to the gods." In a good sense, this can mean holy or sacred, but it also mean accursed. Another way to think about this word is that it describes something set apart only for God. Remember, the Jewish concept of purity was from a word that means "to separate" and it specifically meant separating the things dedicated to God from what was "common".
The literal meaning of the Greek word for "truth" is "not hidden," and it means what is real as opposed to how things seem.
Christ is saying that being in touch with reality is what separates his followers from the common world. The reality that they can see, and that others cannot, is that God's law is the motivating power underlying reality. We can think of this law as the "laws of nature," if we like, but when we accept them as God's laws, we are accepting that we do not and cannot understand every aspect of those laws, that is, that most of them are always hidden, as God is hidden.
this is a critical point because "the world order," as Christ describes it, pretends that people understand and can control the laws of nature. They worship "scientism" as explaining the world, make God unnecessary. However, scientism has little to do with true science, that is, the truth. As science progresses, it teaches us more about God's laws, but what it really teaches us is how much we do not know. Today, science admits that vast majority of matter and energy that make up our universe is "dark", that is, unexplained by the laws we have discovered.
Admitting the truth of our ignorance is the first step toward true science. It separates us from the world, those who want to believe that everything is known and predictable, and under human control. Most live in this delusion. God's people live in the truth.
ἁγίασον (2nd sg aor imperat act) "Sanctify"" is from is hagiazo, which means "to separate from profane things and dedicate to God", "to dedicate people to God", "to purify," and "to cleanse externally or internally."
αὐτοὺς "Them" is from autos (autos), which means "the same," and the reflexive pronouns, "myself", "yourself", "himself", "herself", "itself," or the oblique case of the pronouns, "him", "her," and "it." It also means "one's true self," that is, "the soul" as opposed to the body and "of one's own accord."
ὁ λόγος "Word" is from logos (logos), which means "word", "computation", "relation", "explanation", "law", "rule of conduct", "continuous statement", "tradition", "discussion," "reckoning," and "value."