A former Catholic school principal’s whistleblower claims are barred on religious freedom grounds, the Illinois Supreme Court ruled last week.The 6-0 ruling held that Mary Rehfield was serving as a minister as principal of St. Raphael Catholic School in Naperville and therefore the ministerial exception doctrine applied.Rehfield sued the diocese after her 2017 firing, alleging it was retaliation for contacting police about a disgruntled parent’s email and phone threats.After that parent was arrested and criminally charged …