Question:
Does Hebrews 10:26 tell us that a person can be saved and then lost again?

Answer:
No, it does not, and I do not believe that any verse in the Bible teaches that a person can be saved and lost again. The Bible says: “He that believeth…hath everlasting life” (John 5:24).

Hebrews 10:26 says: “If we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sin.” This verse is not talking about those who had received the truth but those who had received the “knowledge of the truth,” and then had “wilfully” sinned by rejecting Christ. They turned from Christ’s sacrifice to other sacrifices to take away sin, but this Scripture says that there is no other sacrifice than Christ’s sacrifice that can take away sin from the eyes of a holy God.
This verse is talking about some Jews who had heard the message of God’s salvation through Christ, but had turned back to offering animal sacrifices (as their forefathers did in the Old Testament) which never took away sins (Hebrews 10:4). We are told that these people were worthy of sorer punishment than those who despised Moses’ law, because they had “trodden underfoot the Son of God, and had counted the blood of the covenant, wherewith He was sanctified, an unholy thing, and [had] done despite unto the Spirit of grace” (Hebrew 10:28,29). God has no choice but to punish eternally in the Lake of Fire every person who refuses Christ as his personal Saviour.