What can use to secure the felt to a banner that I've just made?

I've just made a soccer banner for my daughter's team made out of felt and fabric. The banner itself is a piece of 4ft X 3ft piece of felt. I know that I should probably just sew on the pieces to really secure the banner, but can I spray something on it to reinforce it (i.e. spray adhesive, scotchguard) that's as strong as sewing the items on there?