What is a declaration of unity?
John Dickinson was one of the most valued patriots in early Colonial America. When it came time to sign the Declaration of Independence, he refused on the grounds that he believed that there should be more unity between the colonies first, as well as voicing his concern that the forming nation should secure allies before taking the British on.
No, the noun unity is a common, abstract noun; a word for the state of being united or joined; a word for harmony or agreement. A proper noun is the name of a person, place, thing, or a title; for example: Dr. Unity Powell, MD, Covington, VA Unity, ME; Unity, WI; Unity, NH; and Unity Village, MO Unity Middle School, Mendon, IL "Creating Unity" a poem by Terry Loong
God, as stated in Quran, called all people for unity and cooperation for mankind benefit and prosperity; irrelevant to their religions. Accordingly, if one calls Muslims for unity then it is within the call for all world for unity. Unity doesn't necessarily mean physical unity. It is rather unity in fulfilling goals of peace, love, justice, prosperity, and equality.
The short answer is YES. The path to unity depends on the form the 'leaving' took. If the person simply stopped going to Mass and instead attended services at the Baptist church, then experiencing the sacrament of Confession will bring back the unity. If, however, the leaving was 'formal' let's say a declaration of some kind to the Bishop, to the community or to the public, then it would be proper to formally reconcile first…