One generation passeth away, and another generation cometh: but the earth abideth for ever. The sun also ariseth, and the sun goeth down, and hasteth to his place where he arose. The wind goeth toward the south, and turneth about unto the north; it whirleth about continually, and the wind returneth again according to his circuits. All the rivers run into the sea; yet the sea is not full; unto the place from whence the rivers come, thither they return again.
All things are full of labour; man cannot utter it: the eye is not satisfied with seeing, nor the ear filled with hearing.
The thing that hath been, it is that which shall be; and that which is done is that which shall be done: and there is no new thing under the sun.
Is there any thing whereof it may be said, See, this is new? it hath been already of old time, which was before us. There is no remembrance of former things; neither shall there be any remembrance of things that are to come with those that shall come after.
-Ecclesiastes 1:4-11 King James Version
There are two things that are sinful in this world. The first thing is that humans and animals feed on other lives. This thing is very sinful. Why do we have to take other lives to continue our own lives? The second thing is that both humans and animals must obtain goods in order to continue their lives, and all kinds of evils arise from this. For example, when people open their eyes in the morning, they think about how to make a living and how to earn money; animals start looking for food and mates the moment they wake up. Why do we have to acquire, and keep acquiring? Why our existence must depend on acquiring. I think these two things in our world are simply too sinful. I really think that this world is not beautiful. I saw in the Buddhist scriptures that Buddha Shakyamuni can achieve supreme enlightenment in this world. I feel that he is very great. Moreover, after the Buddha became enlightened, he was able to impart his correct knowledge to sentient beings in the world, which is even greater. I also think that Buddha Amitabha’s world does not have these two things, there is no killing, no acquisition, I think this is the reason why his world is called The World of Pure Land.
In the world we live in: human beings and animals often live on other kinds of creatures, eating meat to satisfy appetite, hurting other lives to prolong own life; furthermore, humans and animals mostly rely on acquisition for their lives, and when they wake up, they all run for interest. Therefore all kinds of evils are induced by interests. "Killing" and "greed" are the ways in which all beings in our world depend for survival. That is why our world is called the "world of desire".
Looking further up, the desires of heaven beings are more indifferent than us, because they no longer survive by "killing and greedy". The celestial beings of the colorless world go further, their desires are lighter, so even their physical bodies are gone.
It is said that human beings originally came from Guangyin heaven when human was metamorphosis rather than viviparous birth. At the beginning of each kalpa, human beings fell to the ground from Guangyin heaven, by eating things from the ground melted into the earth, and entered the world from desire to become now a viviparous person who feeds on corpses and is lustful.
In contrast, in the Pure Land, all sentient beings are metamorphoses, and there is no need to rush for food. Therefore, there is no conflict of interest, no sin to be born, and no killing. Just because the beginning of that world lies in Amitabha's great aspiration before he became a Buddha, and the world mirrored in his wish is so beautiful.
Those who don't want to sacrifice other lives for their own lives, and don't want to waste their lives for interest, can read more Buddhist scriptures, make a wish to go to the Pure Land, and no longer come to this world of Endurance. Although being disgusted with this world is originally a delusion, if there is sincerity in delusion, it is a good cause of regeneration. Amitabha.
All sentient beings are born into the reflected world by their mind. It’s a mirror.