Well, in a “Democracy” (which most libtards believe we have); this would be established by a vote and “mob rule” would determine the outcome.
In a Representative Republic - a representative voted by the people would cast his vote - essentially ensuring that the religious groups with the greatest overall population would determine what Holy Days the taxpayer supported schools would be recognized.
Today, the predominant religious groups are Christian and Jewish; but with the influx of Islamic schools; this could turn bad sometime soon.
Again, the nation was not founded by islamists. It was founded by Christians. Ergo, this nation should be governed to give Christianity priority over all other faiths.