POD: Lyman Stewart dies in 1900, and so does not publish The Fundamentals or provide philanthropic support for the nascent fundamentalist movement. This movement is thus weaker and more disorganized throughout the century, and more marginalized. The more liberal wing of the various denominations is relatively more influential. The more secularized churches have less interest in proselytizing the unchurched, and the nonreligious portion of the population grows in relative numbers to become a majority of the population by the end of the century.
That makes sense. Presidential elections don't really matter in this context--this is a cultural WI, not a political one.