Mother superior in my catholic grade school had me and me droogs in her office for some unremembered criminal offense. We were 8th graders and moving on to high school. She asked us each what HS we were going to. My buddy ‘ moochy ‘, Told her he was going to public HS. She told him it was a mortal sin(on his parents) not to go to Caholic HS if his parents could afford it. I thought that was pretty lame for Sister to say
That’s what was preached from the pulpits in those days. By order of the bishops.
Nowadays, when it really IS a mortal sin to allow your children near a government school, the priests preach nothing.