I used to hear some variation of this: “We Christians haven’t been doing so well in the culture war, but in the long run we’ll prevail because we are having lots of kids, and the secularists aren’t.” This doesn’t seem to be true anymore. The birth rate of Christians–whether evangelicals, other conservative Protestants, and Catholics–has dropped so that it is little different from that of secularists.
America’s overall fertility rate has been about 2.1 births per woman, which is barely replacement level. For conservative Protestants, including Evangelicals, the number used to significantly higher, at 2.7. Today, that has dropped to 2.3.