interesting quote about marriage from a Pilgrim

[JustinL]

I was reading from a set of historical documents called The Annals of America and happened upon this quote from William Bradford, second governor of Plymouth Plantation:

May 12 was the first marriage in this place which, according to the laudable custom of the Low Countries, in which they had lived, was thought most requisite to be performed by the magistrate, as being a civil thing, upon which many questions about inheritances do depend, with other things most proper to their cognizance and most consonant to the Scriptures (Ruth iv) and nowhere found in the Gospel to be laid on the ministers as a part of their office.

What's this about marriage being a religious institution?