Most Protestants believe their salvation is assured once they accept Jesus Christ as their personal Savior. Many call this doctrine by the very familiar phrase, "once saved, always saved." To them, this means that God's grace eternally covers them, and thus they have eternal security that God will save them. God is bound to accept them and to give them salvation no matter what occurs after they accept Jesus. In his worldwide crusades, evangelist Billy Graham has popularized the Protestant hymn, "Just as I am, Lord," which sings the praises of this doctrine.
To us, this idea of "eternal security" is a completely ridiculous concept. God is pure and holy (I Peter 1:15-16). He will not accept people who are not as He is. He forsook His own Son, Jesus Christ, when the sins of the world were placed on Him (Matthew 27:46)! Why would He accept us, who are far more personally sinful, if we failed to repent of our sins and came before Him demanding Him to save us "just as we are"?
An analogy from the real world may be helpful. Just because a criminal is absolved of committing a certain crime does not mean that he will never again be guilty of another crime. For example, if the governor of a state commutes a murderer's sentence, but the criminal commits another crime later in his life, he is not innocent. The law says he is guilty of the later crime.
In the same way, a Christian who commits sin is guilty even though God's grace has covered him in the past. If he continues in the sin until it becomes a habitual way of life, he is in danger of losing the salvation promised to him. Notice Paul's quite concise statement in Hebrews 10:26: "For if we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins."
This is plain. If we sin in rebellion against God, setting our will to go against God and His way of life, the sacrifice of Jesus Christ no longer applies. In essence, we have spit in His face. Paul continues by telling us what applies at that point (Hebrews 10:27-31).
Peter says, "For the time has come for judgment to begin at the house of God" (I Peter 4:17), and if we live a life of sin, we will reap the punishment that those sins deserve. Our God is a God of justice. The idea of "eternal security," then, is foreign to the Bible. It is puzzling how theologians could develop such a doctrine when the Bible repeatedly comments, warns, and advises that we can lose it all through sin.