"Truly God is good to Israel, to such as are pure in heart. But as for me, my feet had almost stumbled; my steps had nearly slipped. For I was envious of the boastful, when I saw the prosperity of the wicked" (Psalm 73:1-3)
Many denominations, especially those who embrace the teachings of John Calvin, teach that it is impossible for a child of God to fall from grace and be lost. But is that what the Bible teaches?
That a child of God can apostatize, fall from grace and be lost is a certain fact. There are many Biblical examples of it.
Under the Old Covenant, consider the Israelites whom the apostle Paul cites in 1 Corinthians 10. In one day, 23,000 of them fell (vv. 1-12). Consider also Judas (Remember both Jesus and Judas lived and died under the Old Law). Acts 1:25 relates that he "fell."
Under the New Covenant there is the case of Ananias and Sapphira, members of the Jerusalem church, who were stricken in the very act of lying to God (Acts 5:1-11). There is also Demas, one of Paul's fellow-workers. He went back into the world (2 Tim. 4:10). The Christians at Ephesus were said to have "left their first love" (Rev. 2:1-5). Simon the sorcer, who lived in the city of Samaria, was lost, then saved, then lost, then saved again (Acts 8:4-24).
If I were to warn you about something that did not exist, you would think I was a fool. If one can not be lost when once saved, then God, Christ and the Holy Spirit are foolish because they repeatedly warn against it. Jesus, in Matthew 26:41, said, "Watch and pray, lest you enter into temptation. The spirit indeed is willing, but the flesh is weak." In Hebrew 3:12 "brethren" are warned not to depart from God. 1 Corinthians 10:12 warns the child of God who thinks he stands to take heed lest he fall. 2 Peter 1:10 warns, "Therefore, brethren, be even more diligent to make your call and election sure, for if you do these things you will never stumble," thus establishing beyond a shadow of doubt that the child of God can fall from grace.
God will spew the apostate out of His mouth (Rev. 3:16). The fallen one is blotted out of the book of Life (Ex. 32:33; Rev. 22:18-19). The backslider is gathered out of the kingdom (Matt. 13:41); unfit for the kingdom (Luke 9:62); fit only to be trodden under the feet of men (Matt. 5:13); and as a pig and a dog whose latter state is worse than his first (2 Pet. 2:20-21).
When a Christian falls from grace and apostatizes, everyone loses. The church loses a member, God loses a worker (2 Cor. 6:1), his brethren lose a brother (2 Tim. 4:10), the community loses a Christian's influence, and, most importantly, the backslider himself loses his soul (John 15:1-6).
While warning against falling, the New Testament also provides help to keep one from falling. The first thing one must do is to take heed of himself and his relationship to God. 1 Corinthians 10:12 states, "Therefore let him who thinks he stands take heed lest he fall." One should "watch and pray" that he does not enter into temptation (Matt. 26:41). He should meet the requirements for growth as a child of God (Acts 20:32; 1 Pet. 2:2; 2 Pet. 1:5-9) for if one is not progressing in the faith, he will be falling away from it for "once saved always saved" may sound pleasant, but it is not true.