How is it anyone who is truly trusting in Christ would do something like that? How can you conceive of someone who loves the Lord being so worldly? The only way I can see anyone making such a decision is that they were not saved in the first place. Anyone who has experienced His love, grace, mercy, peace, comfort, blessing, provision, and power would not do that. And anyone who has truly believed has, in fact, experienced all those things. You are talking of unbelief, not belief abandoned.
I hear you saying that only unbelievers struggle with temptations to worldliness and, therefore, the many exhortations and warnings in the Bible are for them, not for real believers. I wish that were true, but temptation and the possibility of failure are a normal and expected part of every Christian's life. I'd be shocked if you disagreed with that.
As powerful as the love of God is in the believer's life, it's just a fact of life that real Christians are susceptible to sin and failure. That being true, it's understandable that the warnings to not fall away could be very much for the genuine believer in Christ, and that the possibility of a change of mind exists for them, too.
I'm wondering if the faith that does not persevere doesn't always mean that faith was not sufficient to save to begin with (though that's possible, of course), but rather that faith
was simply not able to persevere. After 27 years of being a Christian I think I can see that truth in my own walk.
I'm stronger today than I have ever been, but I know that even before in my weaker faith, a faith that may not have been able to persevere to the extent it can today,
I was still very much saved by that faith, just not as able to persevere the way I can now at this point. I've never fallen away, but I can clearly see in these last few years that my faith, the saving faith I've had all along,
is more able to persevere and resist failure, not now capable of saving me where it was not before.
Just as we were saved by God's power through faith, so it is that we also persevere by God's power through faith:
"This inheritance is kept in heaven for you, 5 who through faith are shielded by God’s power until the coming of the salvation that is ready to be revealed in the last time. 6 In all this you greatly rejoice, though now for a little while you may have had to suffer grief in all kinds of trials. 7 These have come so that the proven genuineness of your faith—of greater worth than gold, which perishes even though refined by fire—may result in praise, glory and honor when Jesus Christ is revealed. " (1 Peter 1:4-7)
The point being, it's clear from this passage that if you do not continue in faith--
the thing Peter says we are shielded by God's power through until the day of salvation--you can not continue to be shielded by God's power until the day of salvation. Which is contrary to what some say that even losing your faith can not separate you from God's power to keep you.
Peter says faith is in fact
how God keeps us to the day of salvation. It reasons that if you remove faith you have removed the very thing through which God keeps you! In addition, the suffering we endure not only shows the genuineness of that faith, but also refines it,
making it more able to persevere, not making it now able to save where it could not before.
The bottom line is, 1) You can not remove faith and expect to be saved on the day of wrath. The question is can we really stop the believing that shields us until that day? As I said before, the very fact that we--believers still susceptible to the temptations of the world despite the love of God--are warned not to do that suggests to me that it is in fact possible. And 2) the refining of faith is not making faith that could not save before now able to save, but rather making faith able to persevere.