Obeying the gospel involves believing it.
Rom 10:16 But they have not all obeyed the gospel. For Isaiah says, "Lord, who has believed our report?
In Romans 10 Paul contrasts those who seek justification through obedience to the law (as salvation by works Christians also do), with those who believing the gospel abandon seeking justification by obedience to the law and replace it with trusting in Christ, as it is written "But the righteousness of faith speaks in this way ... that if you confess with your mouth the Lord Jesus and believe in your heart that God has raised Him from the dead, you will be saved. For with the heart one believes unto righteousness, and with the mouth confession is made unto salvation. For the Scripture says, "Whoever believes on Him will not be put to shame." For there is no distinction between Jew and Greek, for the same Lord over all is rich to all who call upon Him. For "whoever calls on the name of the LORD shall be saved." Rom 10:6,9-13
That's obedience to the gospel
I agree. Calling upon the name of Lord is an action or a work.
Sometimes it involves 1 John 1:9.
God's grace. How sweet the sound.
Nobody can be saved without God's grace as their entrance gate and as their foundation.
But obedience or faithfulness to the Lord doesn't stop there.
Why would it unless one is loyal to something else other than God, right?
Anyways, what do you make of verses like Galatians 5:24 that says they that are Christ's have crucified the affections and lusts? Romans 6 says something similar. Jesus says if we do not take up our cross we are not worthy of Him. What does Jesus mean by that?
Anyways, when you read Romans 10, you also have to read Romans 11:22 that says this:
"Behold therefore the goodness and severity of God: on them which fell, severity; but toward thee, goodness, if thou continue in his goodness: otherwise thou also shalt be cut off." (Romans 11:22).
So it's a balance. God's grace and being faithful to Him by continuing in his goodness (or good ways).
You said:
Heb 4:10 For he who has entered His rest has himself also ceased from his works as God did from His.
Heb 3:19 So we see that they (salvation by works Christians) could not enter in because of unbelief.
Heb 4:11 Let us therefore be diligent to enter that rest, lest anyone fall according to the same example of disobedience (of the salvation by works Christians)
If you were to skip back a chapter we read this.
11 So I sware in my wrath, They shall not enter into my rest.)
12
Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
13
But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.
14 For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end;" (Hebrews 3:11-14).
Anyways, Hebrews 4:2 says, "For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it."
They did not mix in faith for them that heard it. They did not believe in Jesus as their Savior.
"Let us therefore come boldly unto the throne of grace, that we may obtain mercy, and find grace to help in time of need." (Hebrews 4:16).
Certain Hebrews were not coming bold before the throne of grace to be forgiven by Jesus.
This was not an issue of Grace by Faith + Works Faith.
The reference to "Ceasing from own's works" is ceasing from the Jewish man made religious system that did not even obey God's Old Covenant ways (even when the Old Covenant was in effect before the cross). The Pharisees made salvation into a system of man directed works alone salvationism without God's grace. This is evident if you were to read the Parable of the Tax Collector and the Pharisee. The Pharisee did not humble himself like the Tax Collector so as to cry out unto God for forgiveness over his sin.
You said:
Heb 3:14 For we have become partakers of Christ if we hold the beginning of our confidence steadfast to the end,
But if you were to skip back up to verses 12-13, it says a person's heart can be hardened by the deceitfulness of sin and they can depart from the living of God as a result.
You said:
Confidence, trust, faith, these are the things that salvation by works Christians lack and as such are disqualified.
That is strange. That is not what I read in Matthew 7:23. Jesus does not say, "Depart from me because you did not believe in my finished work on the cross alone and you trusted to do good works in addition to my grace." Jesus actually says words that are the exact opposite to that line of thinking. Jesus says to certain believers who did certain good works that He did not know them and that they worked iniquity or sin. So yes. Iniquity or sin is enough for the Lord Jesus to say to a believer to depart from Him. It's in red letters as plain as day (or black and white letters depending on your Bible) in Matthew 7:23.