Whomever wrote Hebrews seemed to think so:
Hebrews 6:4-6It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, who have tasted the goodness of the word of God and the powers of the coming age and who have fallen away, to be brought back to repentance.
Jesus seemed to think so...
Matthew 24:8-13
8 All these are the beginning of sorrows.
9 Then shall they deliver you up to be afflicted, and shall kill you: and ye shall be hated of all nations for my name's sake.
10 And then shall many be offended, and shall betray one another, and shall hate one another.
11 And many false prophets shall rise, and shall deceive many.
12 And because iniquity shall abound, the love of many shall wax cold.
13 But he that shall endure unto the end, the same shall be saved.
2 Peter 2:20-22 ESV
For if, after they have escaped the defilements of the world through the knowledge of our Lord and Savior Jesus Christ, they are again entangled in them and overcome, the last state has become worse for them than the first. For it would have been better for them never to have known the way of righteousness than after knowing it to turn back from the holy commandment delivered to them. What the true proverb says has happened to them: “The dog returns to its own vomit, and the sow, after washing herself, returns to wallow in the mire.”
The saying is trustworthy, for: If we have died with him, we will also live with him; if we endure, we will also reign with him; if we deny him, he also will deny us;
James 5:19-20 ESV
My brothers, if anyone among you wanders from the truth and someone brings him back, let him know that whoever brings back a sinner from his wandering will save his soul from death and will cover a multitude of sins.
And you, who once were alienated and hostile in mind, doing evil deeds, he has now reconciled in his body of flesh by his death, in order to present you holy and blameless and above reproach before him, if indeed you continue in the faith, stable and steadfast, not shifting from the hope of the gospel that you heard, which has been proclaimed in all creation under heaven, and of which I, Paul, became a minister.
Galatians 4:9 ESV
But now that you have come to know God, or rather to be known by God, how can you turn back again to the weak and worthless elementary principles of the world, whose slaves you want to be once more?
Revelation 2:4 ESV
But I have this against you, that you have abandoned the love you had at first. Remember therefore from where you have fallen; repent, and do the works you did at first. If not, I will come to you and remove your lampstand from its place, unless you repent.
Mixed multitudes. Goats and sheep. Wheat and tares. Four type of soil. Time shows the true nature of each, but it does not change it.
The verse in Hebrews makes salvation a one shot deal. You blow it and you’re done for good. Can’t be saved again. Do you agree with that?
The verse in Matthew 24 is about the Tribulation period and is not applicable to someone who is saved by grace through faith in the church age. That verse has been misapplied by some religious institutions to hang a person’s salvation over their head.
12 Peter 2 may not even mean actual believers, but those who have been exposed to the Truth of the gospel and choose to reject it.
2 Timothy 2 Peter denied Christ and what was Jesus’ response?
James 5 is a tough one and could make a case for your point. I’d be interested in other’s take on it.
Colossians 1 doesn’t say the person wasn’t saved but that they will not be able to stand before God holy, blameless, and above reproach. IOW, standing before the judgment seat of Christ, they will hang their heads in shame for not living as they should have.
Galatians 4 talks about falling back into legalism. Doesn’t say the person isn’t saved any more.
Revelation 2 was written to the church body, not the individual believer.
Would you agree the verse cited in Hebrews also says if you can lose salvation you can never get it back?