Doesn't the Bible teach that once you come to Jesus you can never lose your salvation?
Jn. 10:28 states "and I give unto them eternal life and they shall never perish, neither shall any man pluck them out of mine hand."
Coming to Jesus, accepting His forgiveness by faith, receiving His grace, we receive the gift of eternal life (Eph. 2:8, Rom. 3:22-25). Salvation is a free gift. It is not something we earn by our obedience. Salvation is by grace through faith. When the Philippian jailer asked, "What must I do to be saved?" Paul responded, believe in the Lord Jesus Christ (Acts 16:30,31).
Belief is a function of the will. The same mind which chooses to believe can choose to disbelieve and unbelief leads to spiritual death (Heb. 3:12-14). If we do not hold our confidence in God to the end, we will develop a heart of unbelief. "He that endures until the end shall be saved (Matt. 24:13). We are saved only if we keep in memory what was preached and live the life of faith (1 Cor. 15:1, 2). I
t is always possible to return to the old life of sin, have our names blotted out of the Book of Life and be eternally lost (2 Pet. 2:19-22, Rev. 3:5, 1 Cor.9:27). The word which Paul uses for cast away in 1 Cor. 9:27 is the same word that is used in Jer. 6:30 for those who are burned and ultimately lost. In Jn. 10:28, when we come to Jesus we receive eternal life.
Just as His coming into the heart by faith brings life, our unbelief brings spiritual death. We cannot be unborn, but we can die. Nothing can take us from His hand except our own choice.