(continued)
An traditional example of living in sin unrepentantly (2) has been King David, who committed murder and adultery and thus fell away from the faith (Read 2 Samuel 11 and 12; Psalm 51). About this third cause Martin Luther once wrote:
“It is therefore necessary to know and to teach that when holy people, aside from the fact that they still possess and feel original sin and daily repent and strive against it, fall into open sin (as David fell into adultery, murder, and blasphemy), faith and the Spirit have departed from them. This is so because the Holy Spirit does not permit sin to rule and gain the upper hand in such a way that sin is committed, but the Holy Spirit represses and restrains it so that it does not do what it wishes. If sin does what it wishes, the Holy Spirit and faith are not present, for St. John says, ‘No one born of God commits sin’ (Smalcald Articles III.3.43-45).”
All Christians sin daily and will do so until death, as John himself says in I John 1:8. The sin that John speaks of in the quotation above (1 John 3:9) is the sin that is continued in without repentance. When such unrepentant sin occurs (whether it be adultery and murder or neglect of the Word and Sacrament, living together outside of marriage, etc.) faith eventually dies and Hebrews 10:26-27 applies.
Though it is true that rejecting the Gospel and living in sin impenitently cause one to fall away, these causes happen more easily within certain contexts. Such as? Such as persecution (Matthew 24:9-10; Luke 8:13), false doctrine (1 Timothy 4:1: “in later times some will fall away from the faith, paying attention to deceitful spirits and doctrines of demon”), or neglect. (Hebrews 2:3:“how will we escape if we neglect so great a salvation?”). Christian history is littered with the sorry examples of Christians who fell away from their faith in the face of persecution, who fell tragically through false doctrine, and who fell unknowingly through neglect of the preached Word and Sacrament, worship, and the body of Christ. Persecution, false doctrine, and neglect don’t actually cause apostasy. But they create a climate in which falling away can easily happen.
I hope that helps. If not, there’s always booing the Dodgers LOL