Many sincere Christians believe this. But this isn't what I see in the Bible. It's true that as long as one makes the choice, prayerfully, to remain in Christ - they are safe and are kept from falling away. But there's evidence that not all new converts do remain faithful to Him and there's evidence that some do fall away. Look at a list of verses on the subject of how some fall away and how the scriptures warn believers from falling away (there is no longer danger of it happening to those who have been proven through hardships, and have become solidly fully surrendered to God, though):
https://www.openbible.info/topics/falling_away
Putting up a general search really is not acceptable! Next time, pull out some of those verses, in context, not cherry picked, and explain why they support your beliefs. Of course, you can continue being lazy, and posting links like this, but be assured, few will click on the link, because you have not even had the courtesy to give an explanation for what you believe the verse says!
Plus, these searches are one sided. And 1 verse doesn't begin to look at the whole meaning of the passage. A good example is Psalms 14:1
"There is no God"
I looked up this phrase, and it is all over Scripture. But each time, when I looked and the verses before and after, in the chapter, in context to the people being written to, and the time, I find this phrase is qualified.
"The fool says in his heart,
'There is no God.'
They are corrupt, their deeds are vile;
there is no one who does good." Psslm 14:1
In context, that phrase was NOT saying there is no God, instead, the verse is saying that this is what fools say, and also disbelievers in God are corrupt, vile, and do no good.
I could give you 10 more examples, suffice it to say, your hermeneutics is faulty, when you post a link to a topic without explain the verse in context
Moving on to my main point, God clearly states that those who fall away never really were on of the elect. (If you don't believe in the elect, that's too bad, because the Bible uses that term to describe believers!)
"Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come. This is how we know it is the last hour. 19 They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us." 1 John 2:18-19
Here John refers to these people first as antichrists, and when they left the church, it was because they were never saved in the first place!
If someone belongs to Christ they will not slip away! Either we belong to Christ, and we are believers, or we don't belong to Christ, and we never belonged to Christ. None of this "once a Christian. If you don't pull yourself up by the boot straps, then you have failed." That is the definition of a works gospel!
In fact, since God saved us, totally, if we fall away, God has sinned by allowing us to walk away! Of course, no one will ever admit that, but it basically comes down to God saving us, and not being powerful enough to hold onto us. That is not the God I serve, I serve the sovereign God of the universe! (No, I don't believe in free will when it comes to salvation! We cannot make the choice, as dead people to save ourselves. We do not have the power to save ourselves, and we certainly do not have the inclination!)
Here is a basic passage, explaining what happens when God saves us!
"3 Blessed be the God and Father of our Lord Jesus Christ, who has blessed us in Christ with every spiritual blessing in the heavenly places, 4 even as he chose us in him before the foundation of the world, that we should be holy and blameless before him. In love 5 he predestined us for adoption to himself as sons through Jesus Christ, according to the purpose of his will, 6 to the praise of his glorious grace, with which he has blessed us in the Beloved. 7 In him we have redemption through his blood, the forgiveness of our trespasses, according to the riches of his grace, 8 which he lavished upon us, in all wisdom and insight 9 making known to us the mystery of his will, according to his purpose, which he set forth in Christ 10 as a plan for the fullness of time, to unite all things in him, things in heaven and things on earth.
11 In him we have obtained an inheritance, having been predestined according to the purpose of him who works all things according to the counsel of his will, 12 so that we who were the first to hope in Christ might be to the praise of his glory. 13 In him you also, when you heard the word of truth, the gospel of your salvation, and believed in him, were sealed with the promised Holy Spirit, 14 who is the guarantee of our inheritance until we acquire possession of it, to the praise of his glory." Eph. 1:3-14
"And not only so, but also when Rebekah had conceived children by one man, our forefather Isaac, 11 though they were not yet born and had done nothing either good or bad—in order that God's purpose of election might continue, not because of works but because of him who calls—" Romans 9:10-11
There are many other verses that could be used to show you your soteriology is wrong, but I'll leave it as this for now!