It's based on Ephesians 2:10, which says (New Living Translation):
For we are God's masterpiece. He has created us anew in Christ Jesus, so we can do the good things he planned for us long ago.
Moms live in messes. The toys, crumbs & spit-up are our natural surroundings. Moms often feel like a mess. We are exhausted, unshowered & hormonal. Our past & present circumstances & decisions can leave us feeling inadequate for God's love & purposes.
A Beautiful Mess -- reminds moms that beauty can come out of our difficult spots. The grime of mothering young children brings the beauty of motherhood. The bruises of life can bring God's redemption.
Embrace Your Story -- reminds moms that our past, present & future can be used for good. God knows where each of us has been, where we are today & has set in motion where we are headed.
(adapted from mops.org)