"IF WE FIND THE CAUSE we shall discover the origin of the mental illness which swept this religion into Full blown CULT."
That's an easy one. The thought is that they are right and are removing the badness to be pleasing to God. The problem with that is that over the years God has become callous to that. Just like Ed Sullivan censored Elvis' swiveling hips but today no one cares, because it is just silly, in the past God saw the development of the holidays and took notice, thought they were stupid, but over the centuries ended up saying "who cares" and "whatever". In the 1930 he saw a people that rejected the holidays, but did he really care? He knew many non-Christians and non-religious rejected them also. What's the difference?
In the Law to Moses, he gave stern examples to the people. Apostle Paul used those as examples. But Christianity died out after the apostles. The meaning of those lessons died out too.