I don’t disagree that people become Christians in various ways. (Gotta say that I’m intrigued by what would be an irrational way to be a believer.) But that doesn’t answer the question: Is it totally impossible that accepting Christianity was not your free-will choice, but was actually God directing your mind subconsciously? How would you even know?
Some of my response to your points here, if I was to offer it, would be more or less the same one I gave you a while back where we briefly discussed Pascal. Do you remember any of that? (If not, that's ok. We've both slept since then).
Anyway, in my effort to keep this as brief as possible, I'll just say that I think an "irrational" way to be a Christian believer is to be one who affirms the contents of the Bible in an utterly fundamantal way such that the substance of the affirmations are drawn primarily from one's emotions rather than any other form of consideration.
By contrast, being "rational" within the bounds of Christianity would then become a human act on a sliding scale of analytic quality, with those persons who are more reflective, thoughtful, studious and willing to appeal to various forms of academic research--and thus analyzing relevant data via various logics--making up the cadre of believers who take the more rationalistic approach (...but with all things considered, of course ...

)
With the above, then, the whole idea and application of "God's Sovereigntly" can be metted out in a more analyzed and scaled way rather than just throwing it out there as if the idea explains itself and somehow denudes the complimentary idea of "human volition" of any substance or applicable meaning.
As for your questions, it is possible that God directed my mind subsconciously to follow Him, but even if that is the case I don't 'know' that He did and the only tell-tale token of that idea is found in the words of the Bible, such as those of Jesus in John 15:16 where He says, "You did not choose me, but I chose you..."
But even with this being the case, again, I don't know
how God does it or if He needs to do so in a totalistic kind of way (being that His power is great, it might not take very much power from Him to draw me, right?). And if He doesn't draw a person in a totalistic way with a kind of totalism such as Calvin would aver for, can I infer that there is still the possibility remaining that this allowance offers me, however minimally, some leeway for making my own authentic decisions about whatever attraction I develop toward Jesus as a figure for my own religious reverence?
Moreover, I'm an Existentialist with my own view on epistemology, so being as such, I assume my freedom exists even if somehow it is secretly being curtailed by God Almighty.
So yeah, great question Jayem: "How would you even know?"
I suspect we can agree that ultimately, Christian belief (and all religious belief) comes down to faith. I won’t argue with faith. In multiple places, the Bible says faith is a gift. If that’s true, then I haven’t been given that gift.
....mmmm. Maybe. But I operate with a different definition of faith than do my more Fundamentalist or Charismatic leaning brethren. Personally, I take faith to be defined as a "whole person, operative response to whatever cognitive and/or conceptual traces we find as given in Reality around us" (however little they may historically or metaphysically seem to be). I don't work with a definition of faith as being some kind of 'blind and purely emotional' state of mind by which full religious affirmation is made. For me, faith is at least partially an aspect of rational capacities, not a response to God despite them.
In my entire life, I’ve never connected with any religion. As my avatar notes, I’m a naturalist.
ok. And similarly, never in my life have I experienced anything that I would cite as truly supernatural. I began with the natural (ala Carl Sagan and such) and explore our world (and religion) through this philosophically ...
I believe everything in this universe is purely a function of matter/energy and the fundamental forces of nature.
I more or less tend to think within similar patterns, but without the sense of absoluteness that you [may] have about it. By corollary, my view on issues of Determinism will fall short of being absolute or decisive either.
Anything claimed to be supernatural is a product of the human imagination. That’s my variety of faith. Honestly, I don’t reject supernatural thinking out of any animus towards religion. I dismiss it because it’s incomprehensible to me. My brain just isn’t wired to process it. (If there is a God, that’s how he made me.) How would it please God if I said I accept him when I really have overwhelming doubts? Wouldn’t God know I’m lying?
Maybe. It could be the case, and since I don't know the extent of your philosophical and conceptual exploration about Christian epistemic issues and/or theology, and since I'm an existentialist, I can say I fully empathize with your mindset. However, at the same time, I'm under the impression that no one human individual knows everything ... call this my Non-Foundationalist Axiom, however oxy-moronic it may sound.
As I see, if there is a sovereign God, who’s will is that I become a Christian, then events will be arranged so that it happens. And if it doesn’t happen, then either there isn’t a God who’s sovereign in all things, or my belief was never meant to be. To me, that’s logical.
Well, this seems logical to you, but I think it's a false dichotomy since, either way, "How would you even know?"
