"If ye believe not that I am He, ye shall die in your sins" (John 8:24).
These are frightful words. St. John Chrysostom tells us (http://www.ccel.org/ccel/schaff/npnf114.iv.lv.html) that Christ came to take away the sin of the world, and that in baptism our sins are washed away and we "put off" the old man, our sinful nature.
Sin is a frightful thing, for it separates us from God. Christ came to free us from our sins and unite us to Himself. But if we choose again the old man, the life of sin, what then? St. John: "Wherefore He said, “He that believeth not is judged already”; not merely through his not believing, but because he departeth hence having his former sins upon him."
A comment sent to me by email: "Fortunately, he added 'IF'".
So true! Christ is Risen!
It seems that it is a whole cloth: Recognizing the Lord, recognizing that we are sinners and recognizing that we need His mercy. If any of these threads is missing the tapestry of His grace is undone and we cannot receive mercy–we will die in our sins, oblivious to the Truth that is all around us. If we cannot see that He is the Lord, the son of God, come to save sinners, how then can we cry out:
"Lord, Jesus Christ, son of God, have mercy on me, a sinner!"
I have sinned, I accepted Christ, I sinned again, I am now damned without remedy.
That is not what the quote said, or what we believe Anathamus.
To expand on what Fr. Seraphim has said, this is in fact a heresy that the Church condemned in the 3rd century. There *is* a remedy — namely, a desire to repent and turn back to Christ, coupled with the aid of Grace through the Sacrament of Confession.