If my tinfoil hat was on a little tighter, I'd say there's a large-scale scheme going on here, entirely about profit-making and bolstering the numbers of fundies in the country.
Think about it: reduce or eliminate immigration, forcing Americans to take the lower-paid jobs that are OSHA nightmares, instead of relying on undocumented immigrant workers. To do this, you need to raise a generation with the expectation that a segment of them will HAVE to take those jobs. To achieve that kind of desperate lower-income tier of the population, you increase the amount of unwanted births, placing millions of children into neglect and poverty.
You have to make sure they can't get an education, so you gut public schools or eliminate them altogether, like that guy in Texas is already trying to do, and you make universities impossible to afford. This gives them very few ways to survive as adults, basically either the military or these terrible jobs. Corporations then benefit from a whole underclass of people desperate to work in sweatshops like it was 1902 again.
Those children that are given up for adoption will end up in fundie households, placed there by a network of Christian fundie adoption agencies, who make good profits on the scheme and raise the kids as fundies, bolstering their numbers. Christian fundie adoption agencies would refuse to let non-fundie or Jewish or Muslim people adopt, for the same legal reasons fundies don't have to bake you a wedding cake.
Meanwhile, the far-right SCOTUS slowly chips away at the rights of gays, women, voters and workers, further prioritizing the rights of corporations over humans. That underclass would be denied the right to vote. Gays wouldn't be allowed to adopt. Women wouldn't be allowed to abort and, if this goes further, which I know they want it to, they would be severely limited in how or when they could use birth control. The insurance may not pay for it, their employer may fire them if they find out they use it.
I dunno, now that I've typed it out, it doesn't sound so far-fetched anymore.