The evil that led to Peter's fall [in denying Christ at His trial] ... is proving the ruin of thousands today. There is nothing so offensive to God or so dangerous to the human soul as pride and self-sufficiency. Of all sins it is the most hopeless, the most incurable. TR 48.4
Peter's fall was not instantaneous, but gradual. Self-confidence led him to the belief that he was saved, and step after step was taken in the downward path, until he could deny his Master. Never can we safely put confidence in self or feel, this side of heaven, that we are secure against temptation. Those who accept the Saviour, however sincere their conversion, should never be taught to say or to feel that they are saved.*It is the privilege of the Christian to know that on his acceptance of Christ he is saved from his sins and can rejoice in this salvation. But neither the Scriptures nor the Spirit of Prophecy writings supports the popular teaching: “Once saved, always saved.” A person may be saved today, but failing to keep his eyes on Jesus and to grow daily in Him, may become self-confident and be lost tomorrow. The apostle Paul declared, “I die daily.” In a sense, conversion is a daily experience.
Study carefully the warning drawn from the lesson in Peter's life. Read it in its full context and in conjunction with the similar statement that follows. You will find the perplexing passage to be self-explanatory. Our Lord would have each Christian rejoice freely in his salvation, the salvation he enjoys daily. And when asked, “Are you saved?” he can with assurance answer yes. He will explain that this experience is one that results in constant dependence on God and in daily Christian growth.—White Trustees. TR 48.5
This is misleading. Every one should be taught to cherish hope and faith; but even when we give ourselves to Christ and know that He accepts us, we are not beyond the reach of temptation. God's Word declares, “Many shall be purified, and made white, and tried” (Daniel 12:10). Only he who endures the trial will receive the crown of life (James 1:12). TR 49.1
Those who accept Christ, and in their first confidence say, I am saved, are in danger of trusting to themselves. They lose sight of their own weakness and their constant need of divine strength. They are unprepared for Satan's devices, and under temptation many, like Peter, fall into the very depths of sin. We are admonished, “Let him that thinketh he standeth, take heed lest he fall” (1 Corinthians 10:12). Our only safety is in constant distrust of self, and dependence on Christ.—Christ's Object Lessons, 154, 155. TR 49.2