1) This comparison to me says more about religion than it does about parenting. Unconditional love and devotion to your baby? The feeling is physical, and the baby is real. To be able to invoke the same feelings for a deity appears more magical to me than parenting, especially for those who have never experienced having a child.
2) American parenting isn't killing marriage. Marriages are killed one at a time by the unique parents that choose to do so. And that's the problem with statistical conceptualizations. It rarely applies to you for those dealing with it at the present. Only in hindsight do the numbers compile anyway, so it really isn't all that helpful.
Anyone in a marriage knows that the will to be together is sacrosanct. Once two capable independent adults decide to part ways, nothing could be easier. The past could have been wonderful, and it's easy to feel good about what was good. But for many couples, divorce is the choice, and often a good choice for them. In other cultures, there are more bonds holding couples together. In the US, it's far easier to be independent or marry again. It's easier to live your life on your terms than on that of social perception or social dogma. Is this a good thing? Who are we to judge? If you feel the stats are tilted in the wrong direction, then we can try and tip it the other way with our own marriages. But "for the stats" is not usually what crosses our minds when we're not getting along.
This is a classic case of "is as does". Nothing is killing anything. This is the shape of the new American marriage.