Fair point. But their faith or ideas they adopted were only part of the decision making process. You can probably argue that it also cemented their determination to do hard things. But being determined to do something versus being capable of doing something is very different. It is our accumulated knowledge through history and our ability to think and be creative that gives us the capability of doing hard things.

I guess what I'm trying to say is determination matters, but at the same time we must not overlook the importance of knowledge and known how. No matter how determined you are, you are not lifting a big boulder without a lever.