Hebrews 6: 17 - 20 (NIV): Because God wanted to make the unchanging nature of his purpose very clear to the heirs of what was promised, he confirmed it with an oath. 18 God did this so that, by two unchangeable things in which it is impossible for God to lie, we who have fled to take hold of the hope offered to us may be greatly encouraged. 19 We have this hope as an anchor for the soul, firm and secure. It enters the inner sanctuary behind the curtain, 20 where Jesus, who went before us, has entered on our behalf.
When I first read this, it didn't make sense. Why would the writer talk about a ship anchor going into the inner sanctuary of the Temple, behind the curtain? This is the Holy of Holies, where God's presence is. A ship belongs on the water, not in a temple. Isn't this a mixed metaphor?
But the NIV may be hurting our understanding some here. It says, "where Jesus, who went before us, has entered on our behalf" (emphasis mine). The Greek says "Jesus, our forerunner". A forerunner was a small boat that took the anchor of a ship and dropped it safely in the harbor. Once the anchor was placed in the harbor, the ship's mates could simply pull the boat into the dock. Once the anchor was at harbor, the ship was guaranteed to make it safely in, no matter what.
Our hope in salvation is an anchor for the soul. Our salvation has already been safely placed in the harbor -- in the Holy of Holies, in God's very presence. We are going to make it. Our anchor is already there, we just pull ourselves in at the proper time.
Hebrews 6 begins with a difficult passage that many think means we could lose our salvation if we fell away, but read in the proper light, we can see that the writer is saying salvation is a one-time thing, not something we receive over and over. Jesus died once for all, and when we trust in him, he places our anchor safely in the harbor of God.