The Fifth Head of Doctrine: The Perseverance of the Saints
Having set forth the orthodox teaching, the Synod rejects the errors of those
Who teach that those who truly believe and have been born again not only can forfeit justifying faith as well as grace and salvation totally and to the end, but also in actual fact do often forfeit them and are lost forever.
For this opinion nullifies the very grace of justification and regeneration as well as the continual preservation by Christ, contrary to the plain words of the apostle Paul: If Christ died for us while we were still sinners, we will therefore much more be saved from God’s wrath through him, since we have now been justified by his blood (Rom. 5:8-9); and contrary to the apostle John: No one who is born of God is intent on sin, because God’s seed remains in him, nor can he sin, because he has been born of God (1 John 3:9); also contrary to the words of Jesus Christ: I give eternal life to my sheep, and they shall never perish; no one can snatch them out of my hand. My Father, who has given them to me, is greater than all; no one can snatch them out of my Father’s hand (John 10: 28-29).
Having set forth the orthodox teaching, the Synod rejects the errors of those
Who teach that those who truly believe and have been born again can commit the sin that leads to death (the sin against the Holy Spirit).
For the same apostle John, after making mention of those who commit the sin that leads to death and forbidding prayer for them (1 John 5: 16-17), immediately adds: We know that anyone born of God does not commit sin (that is, that kind of sin), but the one who was born of God keeps himself safe, and the evil one does not touch him (v. 18).
Daily Confession 