The Bible does not teach that people can lose salvation once it is gained. Rather, it teaches that salvation is a permanent experience accomplished by God’s grace through faith in Jesus Christ’s finished work alone (Ephesians 2:8-9), and no one can add their works to His to gain salvation, therefore no one can lose salvation by failing to work hard enough. A better understanding of what this particular passage is teaching can be found by reading the context.
In this passage chapter, the writer starts the chapter by saying he wants people to move on from repenting from dead works and believing in Christ. He wants them to mature instead of worrying about getting saved all over again, essentially. He then launches into those controversial verses where it can sound like somebody is losing their salvation, but what it says right after that passage captures the heart of it. He says in verse 9, “Though we speak in this way, yet in your case, beloved, we feel sure of better things, things that belong to salvation.” He’s saying that God’s people he’s writing to don’t have to worry about the scary situation he just described! For them, he’s sure of better things, of salvation.
The following chapters describe to this church how the law couldn’t perfect anyone, so Jesus had to come rescue them and sacrifice Himself as a better sacrifice that would last. The message culminates in a beautiful verse in Chapter 10 that says, “…by a single offering He has perfected for all time those who are being sanctified” (Hebrews 10:14). Jesus didn’t just forgive sins on the cross, He took care of the whole picture, forever perfecting in spirit those who would believe. And you can’t lose that once you have it. What Jesus did, as He said on the cross, is finished! For all time.