Hi Everyone
I was reading in I John about the sin unto death. We know by rightly dividing the Word I John is written to the people living during the tribulation.
 
John 2:18 Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time.
 
So if we look at the following verses they may very well mean that ther is no reason to pray for the person who has taken the Mark of the Beast because that is the sin unto death. There is no hope. I cannot think of any other sin that we cannot pray for a brother except that one. John did not mention it because he was not shown it yet. But he did know there would be a "sin unto death"
 
John 5:16 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.
 The next verse tells us all unrighteousness is sin. But we know our righteousness is Jesus Christ.
John 5:17 All unrighteousness is sin: and there is a sin not unto death.
 
And look at the possible "sin unto death"

Revelation 14:9 And the third angel followed them, saying with a loud voice, If any man worship the beast and his image, and receive his mark in his forehead, or in his hand,

Revelation 14:10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb:

Revelation 14:11 And the smoke of their torment ascendeth up for ever and ever: and they have no rest day nor night, who worship the beast and his image, and whosoever receiveth the mark of his name.

Just a thought

Mike W