[boatbums]

“I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that you should pray about that. All wrongdoing is sin, and there is sin that does not lead to death.”

Some sins lead to spiritual death, or eternal separation from God. Catholics call these sins, mortal. Other sins don’t lead to spiritual death. Catholics call these sins, venial

When you yank verses out of their context, all manner of error can slip in. What was John talking about here regarding a "sin unto death"? Here's the passage:

I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life. This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us. And if we know that he hears us—whatever we ask—we know that we have what we asked of him.

If you see any brother or sister commit a sin that does not lead to death, you should pray and God will give them life. I refer to those whose sin does not lead to death. There is a sin that leads to death. I am not saying that you should pray about that. All wrongdoing is sin, and there is sin that does not lead to death.

We know that anyone born of God does not continue to sin; the One who was born of God keeps them safe, and the evil one cannot harm them. We know that we are children of God, and that the whole world is under the control of the evil one. We know also that the Son of God has come and has given us understanding, so that we may know him who is true. And we are in him who is true by being in his Son Jesus Christ. He is the true God and eternal life. Dear children, keep yourselves from idols. (I John 5:13-20)

John's talking about praying for someone who is in habitual sin, that they will repent and be freed from that sinful lifestyle. For some Christians, their backsliding might bring God to take them from this life so that they do not cause shame on the name of Christ. The "sin unto death" would be the kind of sin that a person refuses to turn from and our praying for them will not always bring about their reconciliation with God. But, NOWHERE in this passage does the subject of condemnation to HELL come up. Some people read into that passage that a saved person can become unsaved by a sinful act but that isn't what it says. In fact, it says the opposite. God disciplines us as His children and sometimes that discipline might mean He takes us home if we remain in unrepented sin. We don't stop being His children when we have been born again. he doesn't remove the Holy Spirit from those He has sealed until the day of redemption.

We are saved by grace through faith and not by our works. To say someone can LOSE something they didn't do anything to get is negating that it was a gift of grace. God's grace is so infinite and complete that we cannot snatch ourselves out of His hands - NO ONE can.

[St_Thomas_Aquinas]

Have you ever considered the possibility that you are doing eisegesis, reading Lutheran traditions into Scripture?

We are saved by grace through faith and not by our works.

Your statement seems to me to be a perfect example of eisegesis, considering the impossibility of synthesizing it with the below passage.

What good is it, my brothers and sisters, if someone claims to have faith but has no deeds? Can such faith save them? Suppose a brother or a sister is without clothes and daily food. If one of you says to them, “Go in peace; keep warm and well fed,” but does nothing about their physical needs, what good is it? In the same way, faith by itself, if it is not accompanied by action, is dead.

But someone will say, “You have faith; I have deeds.”

Show me your faith without deeds, and I will show you my faith by my deeds. You believe that there is one God. Good! Even the demons believe that—and shudder.

You foolish person, do you want evidence that faith without deeds is useless? Was not our father Abraham considered righteous for what he did when he offered his son Isaac on the altar? You see that his faith and his actions were working together, and his faith was made complete by what he did. And the scripture was fulfilled that says, “Abraham believed God, and it was credited to him as righteousness,” and he was called God’s friend. You see that a person is considered righteous by what they do and not by faith alone.

In the same way, was not even Rahab the prostitute considered righteous for what she did when she gave lodging to the spies and sent them off in a different direction? As the body without the spirit is dead, so faith without deeds is dead.

***

"If I have the gift of prophecy and can fathom all mysteries and all knowledge, and if I have a faith that can move mountains, but have not love, I am nothing."

We are saved by grace alone, through faith/works done in charity and inspired by the Spirit. Luther undoubtedly read this passage. How he reconciled his novel doctrine of "faith alone" with these passages is ultimately a mystery, but probably related to his scrupulosity.