What does John 17:16 mean?

This repeats the same phrase Jesus used only moments before (John 17:14). In this context, the term "world" refers to the culture and belief system which rejects God and His authority (John 12:31; 1 Corinthians 2:12). Christians are not promised to be taken away from persecution and hardship (John 17:15), but only that God will be with us in those trials. As part of this, believers are expected to be "in" the world, but not "of" the world (1 Corinthians 5:9–10). We cannot bring truth to those who need to hear it unless we are present, engaging the people around us (Matthew 5:13–16; Romans 10:14–15).

That separation from the world's attitudes and thoughts (Colossians 1:13; Romans 12:2–3) earns hatred for faithful Christians (John 14:15). Simply by demonstrating that we honor God, not men, we make ourselves the target of anger and sinful rage (1 Peter 4:4; John 16:1–4).