Religion is brain washing. Stop the brainwashing and you stop religion.

Upbringing.. Raise your children to be rational thinkers.

I doubt that you could ever do that. But, if you want to do one thing to eliminate all religion, you have to address the one thing most likely to cause people to turn to religion.

People need to believe in something to explain that which they do not understand and, therefore, are most likely great. So, the best course of action, but one with which there is no guarantee, is universal education. Knowledge coupled with teaching people to have an open mind and question beliefs is the greatest threat to religion.

Nothing. Fanatics will be born, and the cycle continues. someone is always going to come along and think they are god, and a bunch of idiots will believe that person.

If people cared about what is real more than what they wanted to believe.