But we are not really talking about our football team, even though the big game is on Sunday.
This card is a reminder to come to church, sent to boys of Sunday School age in the 1960's. To generate excitement about the starting day of Sunday School, churches used "Rally Day" cards and many other cards like the ones above as subtle reminders to show up, if you know what's good for you.
Here's one of the older variety, a gem from the early 1900's:
I've posted a few others in the past, quickly accessed here: http://blogaboutpostcards.blogspot.com/search/label/Rally%20Days
So, let's raise our hands to Rally Day, lest they get rapped on the knuckles by a Sister!