Aside from all the trash and the seemingly endless supply of toxic chemicals we pour into the earth every day, man kind has created yet another kind of poison.
This poison takes many different forms, and has caused littlle other than missery and death.
The name of this poison is of course, religion.
Throughout history, religion has been used to jusify an incomprehensible amount of blood shed. It has been used to justify so many horrors, I wouldnt even know where to begin listing them.
Many would argue that such incidents are few and far between in this day and age, which is true, to a point.
There are many parts of the world in which it is perfectly acceptable to kill someone, torture them, rape them in the nam of "god"... For being gay, for being a man, or being a woman, for not believing in the same "god" or for not believing in ANY "god" for that matter.
Even in the more "civilized" parts of the world, religion promotes the belittlement, and persecution of those who are deemed "unworthy" or "of less vallue" etc. than those of an opposing religion, or sexuality, gender or sometimes race. Just because modern "civilized" christians generally dont openly hunt "witches" anymore, it doeant mean theyve stopped being bigots.
The biggest and most widespread religions all place a higher value on one group of people over another. Probably the best example, christianity says men are better than women, gays are abominations, and that we shouldnt mix races. (google if you need to)
Stone, burn, rape and torture the "sinners".
The ONLY reason the above^ isnt still in practice, is because religion has been forced to change, and in many ways, it is starting to lose it hold over us.
I dont mean to say that science is the ONLY reason for the decline of religion, but every time science took a step forward, religion has had to take a step back, even if the religious never admit or even realize it.
Even today, were still trying to convince such people of things that have been tested and proven. Its sad, really.
Science has proven time and time again to be a much more effective tool for the progression and the betterment of the human race, than any "holy book" or so called "god".
I could give a nearly endless list of examples, but ive rambled long enough.

A final note...
Bible thumpers enjoy saying "I cant prove god exists, but you prove he DOESNT exist."

To put it simply, you can neither prove nor disprove the existence of that which DOESNT exist in the firt place.