Ultimate salvation is the end, heaven. Justification is often called, therefore, being 'saved' because the justified in Christ will be savedfrom the corruption and sin of this life utlimately and completely. This is why salvation is talked about as having happened (in that Christ accomplished it in the past once for all) (Ephesians 2:8), continuing to happen (1 Corinthians 1:18), and going to happen (Hebrews 9:28).
Salvation is conditional upon your actions. (1 Corinthians 13:2). That it isn't is a relatively recent development. Not that your actions can gain for you salvation, but that they qualify you for recieving or forfeiting it. The entire New Testament is unanimous (obviously) on this. Nowhere in the New Testament is it taught that you get to be saved by having faith in Christ, living a Christian life and later turning away therefrom. The opposite is cleary taught instead.
What of the believer who continues in or embraces the sins listed in those damning verses that specifically exclude these people?
This question is answered directly, unequivocally in Hebrews 10.
Having therefore, brethren, a confidence in the entering into the holies by the blood of Christ; A new and living way which he hath dedicated for us through the veil, that is to say, his flesh, And a high priest over the house of God: Let us draw near with a true heart in fulness of faith, having our hearts sprinkled from an evil conscience, and our bodies washed with clean water.* Let us hold fast the confession of our hope without wavering (for he is faithful that hath promised), And let us consider one another, to provoke unto charity and to good works: Not forsaking our assembly, as some are accustomed; but comforting one another, and so much the more as you see the day approaching. For if we sin wilfully after having the knowledge of the truth, there is now left no sacrifice for sins, But a certain dreadful expectation of judgment, and the rage of a fire which shall consume the adversaries. A man making void the law of Moses, dieth without any mercy under two or three witnesses: How much more, do you think he deserveth worse punishments, who hath trodden under foot the Son of God, and hath esteemed the blood of the testament unclean, by which he was sanctified, and hath offered an affront to the Spirit of grace? For we know him that hath said: Vengeance belongeth to me, and I will repay. And again: The Lord shall judge his people. It is a dreadful thing to fall into the hands of the living God.
* A clear reference to salvific New Testament baptism. (Galatians 3:27; Acts 2:38; 1 Peter 3:18-21; Ezekiel 35:25-26)—he is addressing those who are currently in Christ, justified, baptized. (1 Corinthians 6:11).
2 Peter 2:20-22
For if, escaping from the pollutions of the world, through the knowledge of our Lord and Saviour Jesus Christ, they be again entangled in them and overcome: their latter state is become unto them worse than the former. For it had been better for them not to have known the way of righteousness, than after they have known it, to turn back from that holy commandment which was delivered to them. For, that of the true proverb has happened to them: The dog is returned to his vomit: and, The pig that was washed, to her wallowing in the mire.
Clearly, for St. Paul, and St. Peter, the "promise" is not unfaithful on God's end, only on our own. He doesn't exclude believers from turning away from the salvation they have in Christ. So it is guaranteed that we will be saved if we live according to the will of the Father, as long as we understand heaven isn't our wage for doing so (Romans 11:35), but a loving reward (1 John 2:4; Matthew 7:21; Luke 6:46).
[Brethren...] For if you live according to the flesh, you shall die: but if by the Spirit you mortify the deeds of the flesh, you shall live.
1 Corithnians 9:24-27
Know you not that they that run in the race, all run indeed, but one receiveth the prize? So run that you may obtain. And every one that striveth for the mastery, refraineth himself from all things: and they indeed that they may receive a corruptible crown; but we an incorruptible one. I therefore so run, not as at an uncertainty: I so fight, not as one beating the air: But I chastise my body, and bring it into subjection: lest perhaps, when I have preached to others, I myself should become a castaway.
Do not therefore lose your confidence, which hath a great reward. For patience is necessary for you; that, doing the will of God, you may receive the promise. For yet a little, and a very little while, and he that is to come, will come, and will not delay. But my just man liveth by faith; but if he withdraw himself, he shall not please my soul.
This is what Jesus teaches, also.
I am the true vine; and my Father is the husbandman. Every branch in me, that beareth not fruit, he will take away: and every one that beareth fruit, he will purge it, that it may bring forth more fruit. Now you are clean by reason of the word, which I have spoken to you. Abide in me, and I in you. As the branch cannot bear fruit of itself, unless it abide in the vine, so neither can you, unless you abide in me. I am the vine; you the branches: he that abideth in me, and I in him, the same beareth much fruit: for without me you can do nothing. If any one abide not in me, he shall be cast forth as a branch, and shall wither, and they shall gather him up, and cast him into the fire, and he burneth. If you abide in me, and my words abide in you, you shall ask whatever you will, and it shall be done unto you. In this is my Father glorified; that you bring forth very much fruit, and become my disciples.
As the Father hath loved me, I also have loved you. Abide in my love. If you keep my commandments, you shall abide in my love; as I also have kept my Father's commandments, and do abide in his love.
Because of the increase of wickedness, the love of most will grow cold, but he that shall endure unto the end, the same shall be saved.
Now they upon the rock, are they who when they hear, receive the word with joy: and these have no roots; for they believe for a while, and in time of temptation, they fall away.
Nowhere does Christ or anywhere in the New Testament say that Christians who murder or sin in the ways described in the passages you mention are for some reason exempt. They must obey Christ in order to recieve the great blessing that is New Testament salvation. Anything to the contrary is alien to the New Testament.
Thou wilt say then: The branches were broken off, that I might be grafted in. [You say] well: because of unbelief they were broken off. But thou standest by faith: be not highminded, but fear. For if God hath not spared the natural branches, fear lest perhaps he also spare not thee. See then the goodness and the severity of God: towards them indeed that are fallen, the severity; but towards thee, the goodness of God, if thou abide in goodness, otherwise thou also shalt be cut off. And they also, if they abide not still in unbelief, shall be grafted in: for God is able to graft them in again.
2 Timothy 2:12
If we suffer, we shall also reign with him. If we deny him, he will also deny us.
2 Peter 2:1
But there were also false prophets among the people, even as there shall be among you lying teachers, who shall bring in sects of perdition, and deny the Lord who bought them: bringing upon themselves swift destruction.
Wherefore, my dearly beloved, (as you have always obeyed, not as in my presence only, but much more now in my absence,) with fear and trembling work out your salvation. For it is God who worketh in you, both to will and to accomplish, according to his good will. And do ye all things without murmurings and hesitations; that you may be blameless, and sincere children of God, without reproof, in the midst of a crooked and perverse generation; among whom you shine as lights in the world.
The New Testament is clear that Christians can just as easily abandon and forsake their priveleged state as children of God (just as Adam did) if they deny Christ by not obeying His commandments (John 14:21; 1 Corinthians 7:19; 1 John 2:3).
Pay close attention to this last passage (since the point is already abundantly clear from the above):
What shall we say, then? shall we continue in sin, that grace may abound? God forbid. For we that are dead to sin, how shall we live any longer therein? Know you not that all we, who are baptized in Christ Jesus, are baptized in his death? For we are buried together with him by baptism into death; that as Christ is risen from the dead by the glory of the Father, so we also may walk in newness of life. For if we have been planted together in the likeness of his death, we shall be also in the likeness of his resurrection. Knowing this, that our old man is crucified with him, that the body of sin may be destroyed, to the end that we may serve sin no longer. For he that is dead is justified from sin. Now if we be dead with Christ, we believe that we shall live also together with Christ: Knowing that Christ rising again from the dead, dieth now no more, death shall no more have dominion over him. For in that he died to sin, he died once; but in that he liveth, he liveth unto God: So do you also reckon, that you are dead to sin, but alive unto God, in Christ Jesus our Lord.
Let not sin therefore reign in your mortal body, so as to obey the lusts thereof. Neither yield ye your members as instruments of iniquity unto sin; but present yourselves to God, as those that are alive from the dead, and your members as instruments of justice unto God. For sin shall not have dominion over you; for you are not under the law, but under grace. What then? Shall we sin, because we are not under the law, but under grace? God forbid. Know you not, that to whom you yield yourselves servants to obey, his servants you are whom you obey, whether it be of sin unto death, or of obedience unto righteousness. But thanks be to God, that you were the servants of sin, but have obeyed from the heart, unto that form of doctrine, into which you have been delivered. Being then freed from sin, we have been made servants of righteousness. I speak an human thing, because of the infirmity of your flesh. For as you have yielded your members to serve uncleanness and iniquity, unto iniquity; so now yield your members to serve righteousness, unto sanctification. For when you were the servants of sin, you were free men to righteousness. What fruit therefore had you then in those things, of which you are now ashamed? For the end of them is death. But now being made free from sin, and become servants to God, you have your fruit unto sanctification, and the end, life everlasting. For the wages of sin is death. But the grace of God, life everlasting, in Christ Jesus our Lord.
The promise of salvation is a one way deal. We must be faithful to Christ, and He is always faithful to us. He will never cast us away, but we can leave of our own accord (free will; Genesis 4:7).