I can tell you exactly when it started renny.
One year we started our school day with a volunteer reading from the Bible, a Psalm or Proverb, nothing that could be construed as evangelism, then ALL stood, hands over hearts, and recited the Pledge. After giving honor to God and country, we were ready to learn. The next year, we were told that it's against the law to read the Bible in school. The system, as well as the students futures started to go down the toilet since.