As an example of cognitive bias, I would normally ignore any "research" by Ken Ham. Then he comes along with something I find plausible. I went to Sunday school and heard the stories you mentioned. As an adult, they are not something you want to regard as truth or use as the basis for a moral code, so maybe they did the job they were supposed to do and turned me away from religion and a belief in any god or gods. This also means that I shouldn't worry too much about my grandchildren being forced to attend Sunday schools as a condition of entry into the local primary schools (bizarrely, that still happens in the UK), as they are intelligent and will eventually work out that the indoctrination they are getting has no basis in reality.