The US was 90% Christian and 5% None just 35 years ago. Today it's 63% Christian and 29% None. That seems pretty rapid to me. It has not reached anything close to a majority yet, so the religious still hold great sway. And the perceived threat from their decreasing belief share pushes extremism.

tbh, that seems less like "rapid secularization" and more like "a slight drop from absolute to merely near-absolute power" to me.

Percentage of reported practice doesn't allow for the cultural and legal effects of religion, and it doesn't map linearly to influence. Remember the political apparatus of the US is designed explicitly to give rural Christians outsize power.