What would it take to put Christmas back in our public schools?

It's unclear who, if anyone, was offended by Christmas and/or its metaphors yet somehow Christmas as we know it has almost disappeared from our schools. Kids today grow up never knowing the pleasure of singing carols in complex harmonies or understanding the way Christmas traditions reflect natural seasonal phenomena in our wintry hemisphere. Worse still, the replacement 'Winter / Solstice' festivals celebrate nothing much at all with insipid, watery jingles that sound more like ad slogans. Should we revert and, if so, how do we bring it about?