Hebrews 6:4-9, Hebrews 10:26-29 and 2 Peter 2:20-22 have been used by some to say the Scriptures teach that one can lose their salvation after they have been saved as result of returning to a life of sinful practices. Though a believer will sin at times after he is saved (Romans 7:7-25), no genuine believer will ever return to a life that is characterized by sin, as is clearly taught in 1 John where we read: “No one who is born of God practices sin, because His seed abides in him; and he cannot sin, because he is born of God.” (1 John 3:9).
The only way that any of these three passages could be made to say that a believer can lose their salvation would be to ignore the context of the broader passages from which they are taken, and to isolate them from the rest of the Scriptures a whole. In each of these three passages, the individuals under consideration are not those who are genuine believers and are in danger of losing their salvation. Rather, they are in fact the unregenerate who, though they had heard the Gospel message, and had shared with true believers in the preaching and teaching of the word of God, they had never been saved. Consequently, they could bear no good fruit.
These unregenerate individuals are the false prophets about whom Jesus warned us in Matthew 7:15-23, who come to us “in sheep’s clothing”, claiming to be Christians. They will acknowledge Jesus as Lord, and even claim to have prophesied, worked miracles and cast out demons in His name, but they will one day here from Him the words: “…I never knew you; depart from Me, you who practice lawlessness.” (Matthew 7:23, emphasis added).