No longer being a believer rids me of the need to find the "correct doctrine" on "once saved, always saved" (or "incorruptible seed," if one were to insist).
I don't think the Bible's authors agreed on the matter, to be honest. It's only when one posits that there was "one author, but many writers" that the need for a coherent, consistent, correct doctrine becomes necessary.
My advice to you would be, follow the doctrine that inspires you to do the most and greatest good. If you are worried about losing your salvation, don't do anything that would jeopardize it. If you are confident that you're a son of God and nothing, nowhere, nohow can separate you from the love of Christ, then act like it. Don't be a p-grabbing, lying, misogynistic racist boob just because the threat of hell no longer applies to you.
Can a Christian lose salvation? That's for Christians to answer. No matter where you land on that question, there are scriptures to support your view and scriptures that conflict with it. I would think that if God preserves His will in His Word, the fact of such contradictions makes it obvious that it is not a vital concern to Him. And that makes sense. Why would God even WANT to reassure those who, like me, decided to chuck it all because it no longer made sense? I'm not listening to Him anymore! What reassurance does he have for me? "Its okay, you're still my son. I won't send you to hell!"
That might reassure you guys about me, if you believe in incorruptible seed.
Or you think I'm going to hell, if you don't believe in once saved, always saved.
But to ME, the threat of hell is on par with the threat of a lump of coal in my stocking on Christmas morn.
So from YOUR perspective, I think God is far more concerned with encouraging people to keep on believing and praying and being a part of the One Body, and not at all concerned with letting believers know they have an out if they want to rebel.