I find it interesting that you are drawing a distinction between truth and reality. I have also been attempting to do this.
In one sense my heart is a physical organ. It has no door and, interestingly, can be replaced with another person's heart or even a machine without me losing my essence, my Self. But the writer of Revelation means something else when he says "heart" and "door" and one senses that "knocking" means something quite different from what one does to a physical door with one's knuckles. We're talking here about my essence, my Self, that cannot be borrowed or replaced. If we move the the terms "Christ" or "God" in this context, we getting even farther out from terms that can be connected to something actual. We're getting Concept in its purest form, actually. Idea as Idea.
Yet, scripture is always talking about something particular and not conceptually. The voice of all scripture, which is the Holy Spirit, is always speaking from the truth, which is absolute. In this case, the meaning of "heart" could be likened to your essence, or beingness. There is a theological explanation, but it is pointing to the seat of your personality (your inner man), or the totality of your being, or the ultimate intention of your self. I will also add that truth is not distinct from reality, but that it is what underpins it. What we believe about the truth is what constitutes our worldview, and our worldview is like a pair of glasses that we wear. What will see will match what you already believe aprioi because you are interpreting everything you see through those beliefs (glasses).
You're not aware of it, but there is a tri-unity to your being, which is body soul and spirit. Here is a helpful diagram:
http://www.faithandhealthconnection.org/uploads/spirit-soul-body-mind-emotions-will.jpg
In any case, God is speaking to you, each and every day. There is a reason you are here in this forum having these discussions, as well as studying the scriptures. Perhaps you are like me in that you will have to have these impressions about life completely broken down and shattered into a million pieces before you come to accept Jesus Christ as Lord. I hope you are less stubborn than I was.
You seem to be interested in the truth, which is why I believe you will find it. If you could just understand and follow this one scripture, though, you could skip many of the trials you will face:
Proverbs 3:5
Trust in the LORD with all thine heart; and lean not unto thine own understanding
God is letting you know, here, that your wisdom isn't going to get you there. That you are unable to comprehend the things of God by yourself, and that until you surrender your understanding to Him, you will only be going around in circles.
Revelation comes when you open the door and He shines His light into your life. Until that time, you will not be able to tell light from darkness, and in fact you will think your darkness is light. When the light in you is darkness, how great is that darkness!
Romans 1:18-21 is really more about mankind being a moral being, with that morality purportedly being manifest in the very workings of the universe (I tend to agree but that is really a new topic) than about making an Apologetic for the existence of God. If we turn the page into chapter 2, we get the point--the "therefore" as it were:
It's not, "You, therefore, have no excuse, you who don't believe in God," but "You, therefore, have no excuse, you who pass judgment on someone else."
He's going to use this reasoning as his springboard into a discussion of law and faith.
I will have to disagree with your interpretation here. Let me ask you a question; do you believe this because this was the natural interpretation, or do you believe this because you rejected the assertion that God has provided you evidence and then you found a way to interpret away my conclusion? That isn't how proper exegesis works. We understand everything in context, and we let scripture interpret scripture.
In this case, your interpretation is immediately refuted by the context provided by Romans 2:2
"Now we know that God’s judgment against those who do such things is based on truth. 3So when you, a mere man, pass judgment on them and yet do the same things, do you think you will escape God’s judgment?"
Paul is drawing a dichotomy here between those he was referring to in Romans 1, and the audience he is speaking to Romans 2. The dichotomy is between the Jews and the Gentiles. He is speaking to the Jews here and admonishing them for judging the gentiles for their despicable behavior (notice it says the condemnation spoken in Romans 1 is based on truth) when they are in fact guilty of the same crimes. You can see this further looking down to Romans 2:17-24
Now you, if you call yourself a Jew; if you rely on the law and brag about your relationship to God; if you know his will and approve of what is superior because you are instructed by the law; if you are convinced that you are a guide for the blind, a light for those who are in the dark, an instructor of the foolish, a teacher of infants, because you have in the law the embodiment of knowledge and truth— you, then, who teach others, do you not teach yourself? You who preach against stealing, do you steal? You who say that people should not commit adultery, do you commit adultery? You who abhor idols, do you rob temples? You who brag about the law, do you dishonor God by breaking the law? As it is written: “God’s name is blasphemed among the Gentiles because of you
The Jews were feeling very self-righteous because of their law and looked down upon the gentile because they felt superior for knowing God, but Paul is saying that they are actually no better and maybe even worse.
Romans 1:18-21 is very clear, and doesn't really need any interpretation. What God is telling you is that you have been ignoring the plain truth about Him because of your own selfish motives and desires, which is rooted in a rebellion against His authority. When you are personally autonomous you become a law unto yourself, and many people enjoy that position very much. They get to sit in Gods throne as the King and Judge of everything and everyone and its all about them. What God says is no, I made you, and I am the one in control. He says you can't even get a single breath without His help. He also says, you'll never be happy until He is sitting on that throne. As someone once said, for peace of mind, resign as general manager of the Universe.
Taken plainly on face value, the universe only tells us about the universe.
The universe is itself a discrete body of information by definition. Any information that is not a part of it is utterly (and I do mean utterly) inaccessible to us. Speculating about it gets us no closer. It it were in any way potentially accessible to us, it would be a part of this universe.
Much as a painting tells us about the painter, the creation tells us about the Creator. Yes, I agree that we have no access to truth on our own. To know the truth we would need to be omnipotent. There is however another option, which is that an omnipotent being could reveal the truth to us. That is what Jesus Christ did when He revealed His Fathers love for the world by His death on the cross.