Decrypt hidden message

A little boy opened the big and old family Bible with fascination, looking at the old pages as he turned them. Then something fell out, and he picked it up and looked at it closely. It was an old leaf from a tree that had been pressed in between the pages.

“Momma, look what I found,” the boy called out.

“What have you got there, dear?” his mother asked.

With astonishment in the his voice, he answered, “It's Adam's Suit!”