Except that it isn’t. People are still irrational – they’ve largely turned from religion, but only to find pseudo-science and “spirituality”: horoscopes, homeopathy, traditional chinese medicine, weird forms of supposed "buddhism" tailored to the needs of those who are middle-aged, well-off and bored, and a wide selection of other new-age-hippie-shit. The majority of people here might be non-religious, but they're still far from being critical thinkers. Many still actively fight what they perceive as the "cold" naturalistic worldview, which they perceive as lacking in beauty and mystery.
Even though religion has largely been recognized as out-dated, people still need some values, some ideals to live their lives by. While religion slowly degenerates, it does seem to leave a gap. Religion has been (successfully) brought to its knees, but no viable alternative was presented to the people. Humanism has failed to step up and fill the void, failed to catch the attention of those who are looking for an alternative, who still seek ritual, celebration, community.
Our culture is distinctly influenced by the Enlightenment, but there is no formal acknowledgement of the values that are the basis of nearly all western constitutions and legal systems. Now that is a mistake that need not be repeated in the US – here we still have the chance. Fighting against religion is not enough, because people who stop being religious do not by default become reasonable - They just substitute one superstition for another. To win the fight, we do not only need to make people turn away from fundamentalism, but towards a culture of ethics, art and science - of compassion, tolerance and reason.