Irrational for sure. Everyone's an athiest when they're born. The natural position is non-belief. Religion is a faith based belief system for something that cannot be proven. Hence, belief in religion is by definition irrational.
Now, if you are saying 'religion' to mean 'societal construct' or something like that, well, that is a different ballgame. Though I don't think you mean that, so the above applies.
Bottom line, the major religions of the world demand someone to suspend rationality to believe. Otherwise the followers would not be followers.
No, nobody is an atheist when they're born. Atheism is the conscious rejection of the existence of god. Agnostic, more likely.
Yes, religion is by definition irrational. Humans generally aren't very rational beings. Love is irrational, it makes us do irrational things, but I'm sure we can agree, on the balance, love is a good thing. Thus dismissing religion on irrationality grounds is not very meaningful.
I also didn't say we should dismiss religion because it is irrational, I said people who were religious were irrational. I believe that still stands.
If anyone asked, I would say we should dismiss religion because it is harmful. Harmful to our stability, harmful to our advancement, harmful to the people that follow it and harmful to the people stuck in it against their will (either country, family or society). Today the negatives of religion far outweigh any good it can do. There was a time and place for religion, but we have outgrown it.
Most of the negatives you mention are perhaps styled in the language of religion, but they're underpinned by deeper causes.
The Middle East isn't solely a religious conflict, it's very much an ethnic one as well. Oppressive countries are oppressive, they're not liberal countries that just happened to read in a book that they should kill and maim those that worship in the wrong way. Closely knit groups (families, societies) are going to sanction deviators regardless of religion.
I disagree with both. We are born atheists, but we can create our own god(s) even without the influence of others. How else would religions come to existence?
It might even be an evolutionary trait or something. Having bigger brains, larger set of emotions etc, we needed something to protect us from the sensation of a meaningless life, injustice, the concept of death, the ending of our consciousness, etc.