I like to sum my reasoning why religion is wrong up in concise terms.
Religion is an invention by man. Not all inventions are good or right.
There are a number of religions, to believe one is to (in most cases) believe all the others are incorrect.
Almost all religions can be traced back to worship of the sun as it provided warmth and food.
Religion came about due to a lack of understanding and thirst for answer to questions.
Religion provided an easy out, an answer that can not be proven, or proven incorrect.
As we gain further understanding of the universe and life, more and more religious beliefs are being and will be disproven.
Religion stifles development. To accept an easy, convenient version of events stops you from searching for more. Imagine where we would be now without the dark ages and religious oppression.
