The most recent of the ISI Books "Lives of the Founders" series is a biography of Charles Carroll, the lone Catholic signer of the declaration of Independence. Written by Bradley Birzer, who is Catholic himself, the book really focuses on the impact of Carroll's religion on his political thought.
I hope to share several little excerpts over time, but I'll start with the following. While He may have been the only Catholic signer of the Declaration, his intentions and hopes for the document sound familiar. Carroll writes:
"To obtain religious, as well as civil liberty, I entered zealously into the revolution and observing the Christian religion divided into many sects, I founded the hope that no one [denomination] would be so predominant as to become the religion of the state."
What is most interesting about his point of view is that, of course, unlike the rest of the signers, Carroll's religion was essentially banned in his State, and indeed he had to go abroad to get a Jesuit education. He couldn't practice law in Maryland at times. His orthodoxy and genuine piety made religious liberty that much more urgent--not that it wasn't important to others, but Jefferson, for instance, would not have been too bothered in practice if his religion, whatever it was, was banned.
More about Charles Carroll later, the book is a good read.