1 John 5:16 If anyone sees his brother committing a sin not leading to death, he shall ask and God will for him give life to those who commit sin not leading to death. There is a sin leading to death ; I do not say that he should make request for this. 17 All unrighteousness is sin, and there is a sin not leading to death.
Hebrews 10:26 For if we go on sinning willfully after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, 27 but a terrifying expectation of judgment and THE FURY OF A FIRE WHICH WILL CONSUME THE ADVERSARIES. 28 Anyone who has set aside the Law of Moses dies without mercy on the testimony of two or three witnesses. 29 How much severer punishment do you think he will deserve who has trampled under foot the Son of God, and has regarded as unclean the blood of the covenant by which he was sanctified, and has insulted the Spirit of grace ?
1 John 5:16 refers to sin leading to death. Would you recognize what this says is if it happened in front of you? According to this text you should be able to. Most people look at this text and recognize that there is one sin in the Bible that cannot be forgiven, that being the blasphemy of the Holy Ghost. But when asked what that sin is most Christians cannot give you an answer. Now as we look at Hebrew 10:26 we can find our answer. The author of Hebrews makes it very clear that the sin spoken of is turning your back on the truth of the Gospel. This is not speaking of some one that has not yet come to Christ after hearing the gospel, for most of us were guilty of that even if only for a short time. This is speaking of someone that has heard the Gospel and recognize it to be the truth that refuses to change his sinful life without repentance. You see some people that call themselves Christians living a lifestyle that God calls abomination without attempting to change or even asking God to help them out of this lifestyle. Sometimes the people will not only refused to change, but they will attempt to justify their actions even gone as far to say that this is what God wants them to do.