There are two ideas I want to discuss in this forum, the idea of a fallen world, and a finely tuned Universe.
The idea of a fallen world is a defense against the Problem of Evil, saying that evil entered the world when people sinned. thus, the Problem of Evil does not bring into question God's goodness and power, because it's man's fault. This "fallen world" idea is strictly contradicted by the Teleological Argument
God created the world. He created it good and very good. Perfect is perhaps one way to describe it. I am undecided however because I currently don't see good as perfect and yet some might argue if it was not perfect it must be flawed somehow. Again I am not persuaded that not perfect means somehow flawed. If we see three similar items for sale in a shop of a type of coffee machine. The difference being that they are degrees of good better best. Three prices. The more expensive has more features. Does this make the least expensive one, the one with lesser features, flawed? I don't think so. Yet I suppose someone might say - it is not the best one. And that might be true for some people. But not for all people. Some people might prefer the least expensive one - because the best features are useless to them. Degrees between good and very good - do not mean that good is somehow imperfect. Sorry for that digression.
God created the world and it was good and very good. He also created the heavens. Sin entered the world through one man. Human choice - decision was the impetus in this case of sin. Sin is not a creation. It is an action or an omission. Evil and Sin are not synonymous. I agree that the problem of Evil does not bring into question God's goodness nor power. I reject the idea that a "fallen world" contradicts the Teleological Argument".
The Teleological Argument (or the fine tuning argument) says that the world is so perfect, that a God must have created it.
I am not sure I agree that this is how the TA ought to be represented - but assuming for the sake of your argument you are correct. Let us continue to your discussion.
So what is the problem with these two mindsets?
The fallen world describes an imperfect world around us, and the fine tuned world (from the Teleological Argument) describes a prefect world around us. These two ideas contradict each other, so the Christian must either drop the teleological argument (one of the best arguments for God), or drop the idea of a fallen world (the best response to the Problem of Evil)
if you think the world is so fallen and bad because of sin, stop trying to find design in everything!
Hmmm. Firstly, do Christians suggest that the "fallen world" is referring to the "world" as defined as everything including the animals, plants, and the environment? Or is it just related to humanity and their relationship with God? Secondly, when Christians talk of a "fallen world" what does "fallen" mean? Does it mean 1, absolutely rotten, 2, tainted like a drop of ink in a glass of water, 3, some middle ground? In other words, what is the difference between a non-fallen world and a fallen world?
Christians believe that humanity is capable of doing great and wonderful things. And it is also capable of doing evil and monstrous things. Humanity can do good because it is made in God's image. And yet since God's image in humanity has been tarnished, it also is capable of evil.
Personally, I think it is human nature which has fallen in the primary sense. Nature or the world is also impacted. Hence why we talk of the entire world groaning. Yet the TA as you put it - and the Fallen World Argument as you suggest - prior to sin entering the world - even on your assumptions is the same.
It is the nature of the fall of the world which is the issue. To what extent does the fall of human nature impact upon the world at large? The Christian view is that the impact is significant for humanity - since sin brought about a division between God and Humanity. And humanity's decision has tainted the world and impacted the world around it ever since. Yet, has this sin or fall so distorted the world that we can not recognize its creator. Has it so distorted it that it actually contradicts who made it?
Even after a house fire - where the house has been altogether destroyed - we can look at the ruins and recognize it has a designer.
My view again is that the fallen world and the sin on it has not so impacted the world that it contradicts the TA.