For the church you should dress for a 'holiday' service. In years past, as recently as the '60-70's, ALL church services found ladies and gentlemen dressed in their "Sunday best", but of course times have changed. Not sure of your age, but if you don't recall those bygone days we're talking a suit or at least a suit jacket for the men and modest dress or 'office' wear for ladies.
Now, the guideline for gentlemen for the actual black tie event:
Black tuxedo with pleated front or stiff wing collar white shirt
Black bow tie, black cummerbund (remember the pleats face ‘up’)
Dark cufflinks such as onyx
Black shiny shoes, black dress socks
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