Once Saved, Always Saved?

Many tell us, “once a person is saved, he cannot be lost. If he is lost, he was not actually saved.” I heard a respondent on the radio last week answer a question about this. Someone wrote in saying that a person he knew was a Christian who genuinely believed, but then fell away. The querist wondered: “What about once saved, always saved?” The answer that was given involved the suspicion that this person didn’t actually believe, but also suggested the possibility that, perhaps, he would come back to the church in the end and not be lost after all. Is this what the Bible really teaches?
The Bible says: “For it is impossible . . . if they [Christians] fall away, to renew them again to repentance . . .” (Heb 6:4, 6 NKJV). It won’t work to say that these were not truly Christians; he says they were “enlightened,” tasted the heavenly gift,” “become partakers of the Holy Spirit,” “tasted the good word of God and the powers of the age to come.” These things cannot be said of one who was not actually in Christ. “If they fall away,” means that their falling away was a possibility.
Paul wrote to the churches of Galatia in response to Judaizing preachers who were “pervert[ing] the gospel of Christ” (Gal 1:7). They were saying that the Gentile Christians needed to be circumcised in order to be saved. These were fellow Christians Paul was writing to. That’s why he called them “brethren” in verse 11 of chapter 1. He tells these Christian brethren in 5:3, 4: “And I testify again to every man who becomes circumcised that he is a debtor to keep the whole law. You have become estranged from Christ, you who attempt to be justified by law; you have fallen from grace.” They had been “baptized into Christ” (3:27), but they would be “estranged” from Him if they went back to the Law of Moses for circumcision; they would “fall from grace.” This means that those would had been saved could do something that would result in them being lost.
In Second Peter 2, we read about false teachers who had once “escaped the pollutions of the world through the knowledge of the Lord and Savior Jesus Christ” (2:20). They were not always in sin. They had once been saved from it. But, being “entangled” by the “pollutions of the world” again, they became like a “‘sow,” who, “having washed, [returned] to her wallowing in the mire’” (v. 22).
Even Paul, if he did not bring his body “into subjection,” could be “disqualified” (1 Cor 9:27). If it was possible for him to be lost, then surely the same is true for us.