My Thoughts on 1 John 5:14-17 on Sin Not Unto Death and Sin Unto Death

These verses can be very confusing until you start to do a deeper study. What does it mean to see a sin unto death and sin not unto death? Opponents of eternal security such as the Roman Catholic institution, anti-Catholic cults claiming to be Christian denominations (such as the Seventh Day Adventists), and preachers like Dan Corner will say, "I/we told you that you can lose your salvation when you sin certain sins!" I thought this would mean the sin of apostasy or the person who died in their sins. Yet, John uses the term "brother". Then again Jewish people referred to each other as such.

Here's an excerpt from John F. MacArthur's article "The Sin unto Death" which somehow agrees with what I think:

First, the sin in question may be that of a non-Christian leading to eternal death. In that case it would be a final rejection of Jesus Christ, such as that committed by those who attributed His miracles to the power of Satan (Matt. 12:31–32). Such ultimate apostasy is unforgivable, as Jesus declared: 

Therefore I say to you, any sin and blasphemy shall be forgiven people, but blasphemy against the Spirit shall not be forgiven. Whoever speaks a word against the Son of Man, it shall be forgiven him; but whoever speaks against the Holy Spirit, it shall not be forgiven him, either in this age or in the age to come. (Matt. 12:31–32) 

Praying for the restoration of such people to the fellowship from which they have departed (1 John 2:19) is futile, because “it is impossible to renew them again to repentance, since they again crucify to themselves the Son of God and put Him to open shame” (Heb. 6:6). John did not forbid prayer for such people, since it is impossible to know who they are. The apostle merely stated that prayer for them will not be answered; God has already made the final decision about their future. Supporting the view that John is referring to unbelievers is the present tense of the participle hamartanonta (“sinning”; the Greek text literally reads “If anyone sees his brother sinning a sin …”); John elsewhere in this epistle uses the present tense to describe the habitual sins that characterize unbelievers (e.g., 3:4, 6, 8; 5:18).

However, the same article also writes this one:

Another possibility is that John is not referring to an unbeliever, but to a believer. According to this view, the sin leading to death refers to a Christian’s sin that is so serious that God takes the life of the one committing it. He put to death Ananias and Sapphira when they lied to the Holy Spirit in front of the church (Acts 5:1–11). Paul wrote to the Corinthians concerning those who were abusing the Lord’s Table, “For this reason many among you are weak and sick, and a number sleep [have died]” (1 Cor. 11:30). The sin is not one particular sin, but any sin that the Lord determines is serious enough to warrant such severe chastisement.

Presbyterian preacher J. Vernon McGee also cites this one:

Someone might ask at this point, "What is a sin unto death?" First, let me be clear that John was not speaking of an unpardonable sin. We are talking about a sin unto physical death, not spiritual death. These people were God's children. He would have never taken them home if they had not been His children. The Lord doesn't whip the Devil's children - He whips only His own children. When His children sin unto death, He will take them home.

Such was also taught in a pamphlet I got back in high school called "Safe and Secure: The Permanence of Salvation". Though, I struggled with eternal security doctrine that long because I thought it was possible to renounce your faith. I lived in fear I might get so worldly that I will end up leaving like Judas Iscariot. Yet, part of me also believed that if you are truly saved then you will endure to the end. It was a struggle and any Christian can struggle with the doctrine of eternal security. Take note some people who don't believe in once saved-always saved don't believe you lose your salvation every time you sin but a lifestyle of sin can lead one to eventually stop trusting Jesus. However, 1 John 2:19 tells us that such people were false converts. 

So why am I more prone to believing in "sin unto death" means apostasy? Well, the way 1 John 5:16 is stated is:

If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.  

This has me thinking that John never said that if you see a brother sin a sin unto death. This would make a lot of sense when we consider false converts. How many have supposedly made a decision for Christ, prayed a prayer, and later departed? I could remember how Paul Washer in many of his sermons on eternal security says, "They departed from us because they are not us." I call them sit-in "converts" who only were seekers but never found anything. Many of them ended up living a life of sin showing signs of having never been truly converted. I think MacArthur's first statement over the other possibility is actually more accurate than the second. However, some Christians can sin unto physical death (such as driving while you're not feeling well) which may also make sense. However, I think this death here refers to eternal death and that people who sin unto death, have committed the final apostasy are labeled as not to pray for them anymore. But we can't be certain who can't be prayed for and that prayers for people may be rendered useless if they have hardened their hearts. It's pretty much like people who receive the mark of the Beast - the sin itself is not unforgivable but Revelation states many times that these people repented not. Hence, that's why I think people who sin unto death are beyond repentance because they have decided to forever harden their hearts.