Meh, lazy thinking on religion and oversimplification of history. Yet, there's absolutely an argument to be made that capitalism has provided wider mobility than the Chinese bureaucratic system, the medieval church or merchant states provided before. But mobility is measurably worse in the US now than mid-century and we can and must do better.
It took most Black folks 400 years to mobilize upwards from slavery under capitalism in America. And many of the civil rights that were hard won in the mid-century have been eroded practically overnight. Racism has always been a cornerstone of capitalism, and still is, condoning exploitation of people by casting them as less than human. Upward mobility is measurably harder if you're brown. I agree, we must do better.