All of that and only one scripture reference? And nothing about the Holy Spirit who is the Christians guide, teacher and keeper.
Once a person comes to Christ as a repentant sinner to be saved by him, he is sealed with the Holy Spirit, Ephesians 1:13 and is eternally saved. Nothing can separate him from the love of God that is in Jesus Christ, Romans 8:35.
If you understood the Gospel you would understand that the Christian cannot lose his salvation. After the Christian is sealed with the Holy Spirit God places him "In Christ",
"For you are dead, and your life is hid with Christ in God" Colossians 3:3.
Now answer this. If the Christian is hid with Christ in God, how can he lose his salvation?
He can't. Now, there are some that profess faith in Christ and fall away. These people never did really have faith in Christ, they were counterfeits. There are many counterfeits that when trials or persecutions come they fall away. But the true born again Christian, 1 Peter 1:23, cannot fall away no matter what comes.
Did King David lose his salvation when he sinned? Of course not. How about the apostle Paul who referred to himself as the "Chief of Sinners?" 1 Timothy 1:15. Does sin separate us from the love of God that is in Jesus Christ? Paul said that NOTHING can separate us from the love of God that is in Jesus Christ, Romans 8:35.
Once sealed, always sealed. There is no unsealing in the Gospel. The Holy Spirit is God's mark of owner ship. Once you receive his mark you are eternally his. The Holy Spirit is only given to those who hear and believe the Gospel, Galatians 3:2. In the Gospel we are sanctified, justified and redeemed, 1 Corinthians 1:30. Maybe you should try to find out more about this Gospel so that you can teach according to the scriptures.
Firstly, without the holy spirit we are dead to God.
There is no way we are eternally saved just because we say we believe and are baptised. Once we repent, we are saved from our past sins, then we are to turn from sin. If we have the holy spirit he will be saving us and turning us from sin everyday, and it's up to us to listen and obey, if we obey God and live by his will then he keeps us secure. If we carry on living by the lusts of our flesh, and putting ourselves first then we're turning away from God and we will die in our sins.
"For you are dead, and your life is hid with Christ in God" Colossians 3:3.
Now answer this. If the Christian is hid with Christ in God, how can he lose his salvation?
Being hid with Christ in God means that Christ is in our hearts and he's living through us and you don't see us anymore. Our old life has gone and we are living in a new and living way in Christ and you see Christ in his people. You will know them by their fruits.
If we're truly risen with Christ, then we are dead to this world and this world and the works of it should mean nothing to us.
If we turn back to our life in the flesh and live to please ourselves then we die and we're not being saved.
Jesus clearly said, those who endure to the end, the same shall be saved.
We are to deny ourselves, bare our cross and follow Christ. Those who are not willing to bare their cross are not worthy of him.
Also, after what you have quoted in Colossians 3 there is this
Mortify therefore your members which are upon the earth; fornication, uncleanness, inordinate affection, evil concupiscence, and covetousness, which is idolatry:
For which things' sake the wrath of God cometh on the children of disobedience:
In the which ye also walked some time, when ye lived in them.
But now ye also put off all these; anger, wrath, malice, blasphemy, filthy communication out of your mouth.
Lie not one to another, seeing that ye have put off the old man with his deeds;
And have put on the new man, which is renewed in knowledge after the image of him that created him:
If we have truly put on Christ, then we should be turning from sin.
Sin brings death
James 1
Then when lust hath conceived, it bringeth forth sin: and sin, when it is finished, bringeth forth death
Romans 11
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 8
Therefore, brethren, we are debtors, not to the flesh, to live after the flesh. For if ye live after the flesh, ye shall die: but if ye through the Spirit do mortify the deeds of the body, ye shall live.
We are to modify the deeds of the body to live. If we live after the flesh we shall die.
David suffered terribly for his sins, Paul persecuted Gods people before he was converted. You say nothing separates us from the love of God, well right through the Bible it clearly shows that sin does separate us from God, and I know we all sin, when we do things wrong then realise after, and we should be then going to God to say sorry, and if we've hurt anyone we should put it right. But we should be turning from wilful sinning, if we carry on living by the lusts of the flesh and wilfully sinning, we die.
2 Peter 2
For if after they have escaped the pollutions of the world through the knowledge of the Lord and Saviour Jesus Christ, they are again entangled therein, and overcome, the latter end is worse with them than the beginning. For it had been better for them not to have known the way of righteousness, than, after they have known it, to turn from the holy commandment delivered unto them. But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire.
Once saved always saved is a false teaching!