The real issue between those who believing in justificaiton by grace alone through faith alone in Christ alone without works is the definition of the terms involved.
This is especially true with the term "works"! What is a "work"? Jesus defines evil works or what the Bible calls "sin" to include the motives and thoughts of man. His outward actions are simply the extension of those motives and thoughts. Negatively, bad or evil works or what the Bible calls sin begins in the heart and that is exactly why Christ can say that if a man even casts a look of lust he has violated the commandment not to commit adultery already IN HIS HEART. The same is true with every other commandment of God. God looketh upon the heart.
Therefore WORKS both good and evil are inclusive of motives, attitudes and thoughts. What is faith or the lack thereof?
Most justification by works denominations define justification by faith to be equal with faithfulness, thus inclusive not only of the attitude of the heart but the actions manifesting that attitude. James chapter two is their favorite text to reinforce this definition. Therefore, where there is no works there is no faith. However, this interpretation is exactly what the Bible defines as justification by "works."
The truth is that justification by faith has to do solely with the proper object of faith rather than the actions of faith. The actions of faith are consequential but not causative (Eph. 2:10). Justifying faith is always described by the prepositions rather than by verbs of personal actions (Rom. 3:24-26). What justifies is faith IN the person and work of Christ as it is Christ's works rather than ours that justifies before God.
Furthermore, justification by faith in Christ is a completed action that stands completed because it is sustained by the power of God (Rom. 4:11, 5:1-2).
James is speaking about the evidential proof of justification before the court of human observation (James 2:14-18) rather than before God (Rom. 4:1). James says "show ME....I will show YOU" by my works. Abraham demonstrated his faith before his son and servants. Rahab demonstrated her faith before the two spies, her family and all of Israel with the red cord hanging from the window.
The issue is where does the sustaining power of justifying faith reside? With the believer or with the Holy Spirit? John says those that went out from us were really not of us for if they had been of us "THEY WOULD NO DOUBT HAVE CONTINUED WITH US." He is speaking in the context of antichrists or those who turn against Christ. The sustaining power of faith is grace (Rom. 5:2) or the power of God (Heb. 12:2; 1 Pet. 1:5) of faith is "kept by the power of God."
Everything that we either do or fail to do is called "works" in the Bible. This is precisely why justification by faith is "of grace" (Rom. 4:16; Eph. 2:8) and not of works and why salvation is "sure to all the seed" (Rom. 4:16).
I agree with what you said above except the part about the justification by works denominations. I think that you are misinformed about what some denominations believe.
However, this thread is not about the security of the believer, so let's get back to why the unsaved believe they can obtain salvation by works.