Anyway, I was confused about this verse the first time I read it.
For since the creation of the world His invisible attributes, His eternal power and divine nature, have been clearly seen, being understood through what has been made, so that they are without excuse.
The verse is saying that the world itself, what has been created, is evidence of God. A point I saw somebody make about this is the sheer amount of complexities in our universe that manage to work. That's a very good point. It's quite unlikely that things like the human eye and spider webs could be as complex as they are without some kind of divine guidance.
But I had another thought regarding this. When I was into all that esoteric nonsense, the visions I had (as a result of trying spiritual things I heard about on the internet without understanding the impact of them), were of otherworldly things, things that looked odd and just carried an inherent feeling different than feelings you'd experience when looking at the real world. Some "felt" pleasant, while some "felt" dark and wicked. (They were all dark and wicked, but, you know.) Those were the result of demonic influence. Even then, though, I had the simple capability of understanding that the feelings in these visions didn't match up with feelings elicited by this world - the world, you understand, that is real and is created by God. But let's not be mistaken, here - this phenomenon isn't just limited to those lost in esoteric fantasies. It happens to everybody who doesn't follow Christianity, and it's absolutely proof of the message in Romans 1:20. Let's begin.
wicca is a perfect example to use here. The belief ties, into nature, an atmosphere of inherent magick (that is, "magic" that is allegedly real) and ethereality; dreaminess, one could say. This belief encourages the use of this magick as well through spells, and it also encourages an admiration and a sense of grandeur in regards to the fantastical world it paints, comparable to some fictional work about elves or something, but made into a reality. Art regarding wicca is, in my experience, usually extremely saturated and colorful.
The problem is, when you actually enter nature, these mystical feelings elicited by the wiccan belief system are not elicited by the actual nature created by God. The magick that is supposedly part of nature, according to wicca, is not present in the woods around us. The artistic interpretations inspired by it, with the exaggerated color saturation and visuals, do not actually reflect what nature itself is. That is because nature is not a sentient entity, is not to be worshiped, and has no ties to alleged "magick". In fact, "magick" isn't real either - humans have no inherent powers like this, it's demons at work, trying to mislead you and get something out of you. (I have done spells in the past! I know how it appears to users, and how spiritually poisonous it actually is!)
new age beliefs are another one. These beliefs focus a lot on spiritual practices. Overall "spirituality" is a big aspect of new age, and you can't get too specific in describing it, since it's a broad term. But generally speaking, new age beliefs tend to promote (the search for) an all-encompassing sense of peace, of calmness, of light, of love. new age things tend to elicit a sense of dreaminess or of some spiritual grandeur, seeing as how "spiritual" it is. new age artwork is usually quite abstract and colorful, from images of energy waves to images representing things related to chakras, and the list goes on.
It may actually sound quite close to Christianity (minus the chakras) when described vaguely like that, and concepts like "light" and "love" and "peace" are things Christians certainly (should) go for, but you forget something when you make flawed comparisons like this. new age hides an inner darkness to it, because it's influenced by demonic practices, and beliefs adapted from other, older, demonic belief systems. For example, the meditation promoted by the new age movement, which is allegedly intended to bring peace and balance, is actually a way to basically swing the door open to demonic influence. When you enter into this kind of meditative state, you're not transcending anything, you're not bringing any balance, you're not doing anything else, because that's not how spiritual things work in our world. It's an illusion, a fantasy. It's only an invitation to let negative forces (ones just like the ones described by Christianity, go figure) work through your vulnerable state. Likewise, the dreaminess portrayed by new age things doesn't reflect the real world. The alleged "higher truths" sought through these meditative practices are just as false as the practices used to find them. The real world that God actually made, is more grounded, and carries a sense of solidity that these misguided spiritual practices don't give you.
Another big one is nihilism. While not a theological worldview / religion (it involves atheism, which is a theological worldview / religion), it's an influential worldview, and not in a good way. Everything I've ever seen pertaining to nihilism elicited extreme feelings of emptiness. It can be compared to an old black-and-white movie with poor lighting, or something, but a scene with no actors or background music - very depressing, to be sure. But here's the good news about that - it's false. It's absolute lies. A poorly-written fantasy. The world isn't inherently empty like that. The feelings elicited by those old, faded, impersonal, black-and-white images do not match up with the colored, active, emotion-filled world in which we actually live. The argument could be made that these feelings are just subjective and aren't, in themselves, evidence that nihilism is wrong. Well, you know, Romans 1:20, the verse that started this post, states that the evidence you seek is in the world itself. Read on...
God paints a picture in the Bible, of a world containing beautiful nature scenes, but ones that don't carry anything inherently special or ethereal, or require worship or admiration. This lines up with the nature of the world in which we live. God paints a picture in the Bible of a world where light and dark are both at work, neither one being universally encompassing. This also matches up with the real world. God paints a picture of a world where there is Earth, Hell, and Heaven. This also matches up with the real world, seeing that the other alleged worlds described by esoteric beliefs are fabrications of demonic influence (that disappear when that demonic influence is blocked), and don't actually manifest in any way in the real world. Seeing that new age transcendence is also a product of demonic practices that hide an inner darkness, the things seen through that can also be determined to be false. The world truly reflects God, and God alone. No other beings, no other deities, nobody else's interpretation of it or anybody else's design. It is truly, truly, clear and evident in the world in which we live. And thus, as the verse states, mankind is without excuse. Any other view is truly a willing disregard of things inherent in our world.
I don't intend to go through every single belief system that isn't Christianity and describe in detail what specific things make it false, but the rule applies to all of them, regardless. These beliefs all paint pictures of worlds that carry atmospheres, visual perceptions, and interpretations of things which don't line up with the workings of the world in which we actually live. God's word, on the other hand, matches up to it completely. And how great it is that this is the case. I wouldn't want to live in any world molded after anybody else's design.
May God bless you all, according to His perfect will. In Jesus' name. Amen.