There are many scriptures that testify that a person can fall from grace if they were saved and were led of the Spirit and went back to living like the world and got caught with their pants down so to speak for they died and were holding unto sin, or they believed they could hold unto sin and be right with God.
Isa 59:2 But your iniquities have separated between you and your God, and your sins have hid his face from you, that he will not hear.
Rom 11:20 Well; because of unbelief they were broken off, and thou standest by faith. Be not highminded, but fear:
Rom 11:21 For if God spared not the natural branches, take heed lest he also spare not thee.
Rom 11:22 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.
Heb 3:7 Wherefore (as the Holy Ghost saith, To day if ye will hear his voice,
Heb 3:8 Harden not your hearts, as in the provocation, in the day of temptation in the wilderness:
Heb 3:9 When your fathers tempted me, proved me, and saw my works forty years.
Heb 3:10 Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.
Heb 3:11 So I sware in my wrath, They shall not enter into my rest.)
Heb 3:12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.
Heb 3:13 But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin.
Heb 3:14 For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end.
There is no difference between the Old Testament and the New Testament for if we go back to sin and hold unto sin then we will be cut off like the Jews that would not go by the truth were cut off.
2Pe 2:20 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.
2Pe 2:21 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.
2Pe 2:22 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.
If they go back to the world and hold unto sin and do not correct it then it would have been better for them to not have known the way of righteousness than to turn from the holy commandment delivered to them.
Heb 6:1 Therefore leaving the principles of the doctrine of Christ, let us go on unto perfection; not laying again the foundation of repentance from dead works, and of faith toward God,
Heb 6:2 Of the doctrine of baptisms, and of laying on of hands, and of resurrection of the dead, and of eternal judgment.
Heb 6:3 And this will we do, if God permit.
Heb 6:4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
Heb 6:5 And have tasted the good word of God, and the powers of the world to come,
Heb 6:6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
If they leave the truth that Jesus is Lord and Savior for an alternate reality whether being an atheist, or another religion, then they cannot be saved again for they went back to the world and forfeited everything and God will not allow them to go through the process of being saved again by having faith, repenting, confessing Christ, and the essentials.
1Ti 4:1 Now the Spirit speaketh expressly, that in the latter times some shall depart from the faith, giving heed to seducing spirits, and doctrines of devils;
1Ti 4:2 Speaking lies in hypocrisy; having their conscience seared with a hot iron;
1Ti 4:3 Forbidding to marry, and commanding to abstain from meats, which God hath created to be received with thanksgiving of them which believe and know the truth.
1Ti 4:4 For every creature of God is good, and nothing to be refused, if it be received with thanksgiving:
1Ti 4:5 For it is sanctified by the word of God and prayer.
This is an example that some will depart from the faith so they were in the faith but they departed from the faith for an alternate reality by embracing the new age movement interpretation of the Bible that shall come out at the latter times which is now which is based on the occult, and evolution, and people are still evolving to be greater and spiritual provided by the New Age Christ, and Jesus is not Lord and Savior, but a good teacher and love, and evolved to be an ascended master and avatar, but not the final teacher which the New Age Christ is the final teacher which they believe will have the Christ conscience and evolve and will share this power with all people who follow him and they will be like the man Jesus spiritual.
These people cannot be saved again for they embraced an alternate reality other than Jesus is Lord and Savior.
But if someone never embraced Christianity but went by the new age movement and comes to the belief that Jesus is Lord and Savior they can be saved for they never left Christianity.
1Co 9:26 I therefore so run, not as uncertainly; so fight I, not as one that beateth the air:
1Co 9:27 But I keep under my body, and bring it into subjection: lest that by any means, when I have preached to others, I myself should be a castaway.
adokimos
ad-ok'-ee-mos
From G1 (as a negative particle) and G1384; unapproved, that is, rejected; by implication worthless (literally or morally): - castaway, rejected, reprobate.
Paul said if he did not keep under his body abstain from sin he would be a castaway.
1Co 10:11 Now all these things happened unto them for ensamples: and they are written for our admonition, upon whom the ends of the world are come.
1Co 10:12 Wherefore let him that thinketh he standeth take heed lest he fall.
When people think they stand and cannot fall they might get relaxed in their walk with God and hold unto sin and think they are alright with God.
Heb 10:26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
Heb 10:27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
Heb 10:28 He that despised Moses' law died without mercy under two or three witnesses:
Heb 10:29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
Luk 12:46 The lord of that servant will come in a day when he looketh not for him, and at an hour when he is not aware, and will cut him in sunder, and will appoint him his portion with the unbelievers.
Luk 12:47 And that servant, which knew his lord's will, and prepared not himself, neither did according to his will, shall be beaten with many stripes.
Luk 12:48 But he that knew not, and did commit things worthy of stripes, shall be beaten with few stripes. For unto whomsoever much is given, of him shall be much required: and to whom men have committed much, of him they will ask the more.
If we hold unto sin then the blood of Christ cannot wash it away, and those that despised Moses law died without mercy, so if we despise to be like Christ abstaining from sin then it will be worse for a hypocritical Christian will have it worse than the world for the Christian should know the will of God, which Jesus said not all people who say Lord Lord will be able to enter heaven for they were workers of iniquity and did not do the will of the Father.
A person can be saved and received the Spirit and fall away from grace which there is no excuse for if a person hates sin, and does not want sin, by the Spirit they can abstain from sin, for a Spirit led life will not fulfill the lusts of the flesh, for they have crucified the flesh with the affections and lusts, and show the ways of the Spirit which then they are not under the law which means the law cannot touch them for prosecution.
Continued,