John 17:10-19
Sanctify them in the truth; your word is truth. (John 17:17 ESV)
Is truth objective? Is it subjective? Does it change based on the situation and individual? Is it constant regardless of circumstances?
People have been arguing about the nature of truth for a long long long time. Philosophers, theologians, and various other thinkers have defined and redefined their take on truth numerous times over the years. That's not to say they're right, or even close. But the general consensus is that truth is personal, flexible, and private—which is false.
Jesus prayed his high priestly prayer and included a lengthy bit about the disciples and what he hoped for them. He asked God to "sanctify them in the truth." A singular declarative statement which narrows truth down to something more pointed than the generalities and vagueness our modern era passes for truth.
Jesus went on to define truth. He said that truth is God's Word. In other words, Jesus believed that the Bible, for him it was the Old Testament, was the truth that God would use to redeem, changed encouragement and instruct his people. I am encouraged to know that Jesus saw our need for centralized truth. I am even more encouraged to find that he had prepared that truth before those men were ever even born.
And here is the big idea for you and I. Jesus wants us to be sanctified, cleaned, and set apart, through the careful reading and application of the Bible. Because it is not enough to think we know truth. No, we need to be in truth.