Like all other parts of the high priest's clothing and actions, the little gold plate on the front of his turban reminded the people that God is holy. His holiness affected how they could enter his presence. God wanted to live with his people, but his holiness would harm them unless he took protective measures. God decides how we can enter his presence, not us.
The Bible's main question is how sinful people can live with a holy God so that God can share his holy character with them. Jesus Christ, the Holy One of God, provides the answer. He is the perfect mediator (Luke 4:34; Hebrews 9:11–15). He did not die only to save us from the consequences of our sins. He died so that God can live in us and create his holy character in us (Ephesians 2:10; 4:22; Philippians 1:27; 1 Peter 1:13–16).