Losing Sight of Your Guide
I understand your confusion, and your panic. I really do. I don't know how much to say, but a few things come to mind right now.
First, the “great and terrible day of the Lord” is not really a period of time (though it dawns and then lasts for all time). It is a great light, a living truth, in which the following Scripture is fulfilled in our own experience, “For there is nothing covered, that shall not be revealed; neither hid, that shall not be known. Therefore whatsoever you have spoken in darkness shall be heard in the light; and that which you have spoken in the ear in closets shall be proclaimed upon the housetops.” (Luke 12:2-3) When this begins to really happen in us (when “the day dawns and the daystar rises in the heart”) it is THEN that we begin to see and feel that that all religion in the world is like a fading leaf when it lacks the pure life and living power of God which saves from sin, transforms the soul, and brings into oneness with Him. Standing on the edge of seeing this, catching glimpses, but not understanding where it leads (or if you're even willing to follow) is the reason for the panic, and also for the other voices in you (or around you) that will say you are crazy.
The thing that “rocked your world” seven or eight years ago was the light of this day, the light of Christ, dawning in your heart (in measure) when you were feeling the Scriptures open to you (like the men on the road to Emmaus). The light made you understand the words of Scripture, and made them seem living and real to you. Now listen, it wasn't that the words made you see the light. No. It was that the light made you see and understand the words, and that is why they felt real and alive, and that is why you perhaps started to study the Bible and read more Christian books. But here people make a very common (and understandable) mistake. They think they have been reached by the words, and so they begin to pursue the words. They want to understand more, see more, feel more of the truth.... and they start reading their Bible like crazy and every good Christian book they can find. But as they do so, they inevitably feel a deadness and dryness and earthliness slowly come over them. What started in the Spirit, falls into the flesh (Gal 3). They may learn a lot, but they see and feel almost nothing of the Truth that first reached them, and the REASON for this is because they lost sight of their Guide. They lost their Leader—Christ, the Light of the world, the Anointing that teaches all things, the light of the knowledge of the glory of God in the face of Jesus Christ. They kept His words, but they lost His light. Every word of Scripture is true, but Truth is only found and experienced in it when the heart seeks and submits to the Light of Jesus Christ.
How do you lose your Guide, you might ask? It's very easy to do. Just as soon as the heart ceases seeking and submitting to the living light of Christ, a night comes over it, “in which nobody can work.” People may think they're seeking Him when their mind is studying words and doctrines, but the thing the Lord looks at, sees, and responds to is always the direction and disposition of the heart. This brings us back to my previous email... because His light doesn't just teach doctrines and meanings of words, it shows you everything in your heart, life, thoughts, activities, pursuits, dreams, culture, etc. that are contrary to His pure nature. And so we keep studying with our brains, eager to learn more... but meanwhile we are disobeying His light in our lives, our hearts, our words, and our goals. Do you see? Christ comes to transform you, not to inform you... and many people adore His words, but hate His nature when it appears (little by little) as a judge and teacher in their hearts. They love what He said, but they crucify who He IS when His light demands a conformity to His image. And when we won't love, follow and submit to His light, then it moves on without us, always heading to the Promised Land, and we are left behind, doing circles in the wilderness, arguing about His words.
I believe this is the big invisible thing that you are catching glimpses of... and you know (rightly) that it's way bigger than you think.
As for your question “How do I live there? How do I stay low?”... there is a great deal that could be said about this, and maybe it would be better to focus on that in another email. The most important thing, however, is that you be WILLING to do so. The “how” is never complicated or difficult, but the willingness to love His light and follow Him is what most people refuse. People rarely if ever fail to grow because they didn't know how. They fail to grow because they're not truly willing to walk in what they DO know. Consider Christ's words in John 7:17. “If anyone wills to do His will, he shall know concerning the doctrine, whether it is from God or whether I speak on My own authority.” And also His words to the Jews in John 8:44 “You are of your father the devil, and the desires of your father you want to do.”