However when someone takes off a coat, it is a way of saying, “I’m comfortable here. I feel safe and at ease with you and I would like to stay for a while.”
Leaving on a coat is a way of saying, “I’m cold and I don’t feel comfortable about staying here with you for any length of time because I am so cold.”
As a cradle Catholic, I am thinking this may in fact be a cultural thing that I’ve never actually really even considered until I read your thread. Because here’s how I would interpret these same coat situations:
When I take off a coat, it is my way of saying one of the following:
A) “There’s so much room in the pew today that I have the luxury of taking off my coat. It is in fact getting just a bit warm in here today.”
B) “Mass is crowded today, but I’m in a mood where I really need personal space right about now, so I’m taking off my coat and placing it behind me. Nobody had better sit close enough to touch my coat because it’s kind of cramped like sardines in this pew already and if just one more person squeezes in, it feels like I’m gonna be pushed out and fall on the floor!”
When I keep my coat on, it is my way of saying one of the following:
A) “It’s good manners to make sure that everyone who comes to Mass has a place to sit, so I’ll keep my coat on as an indication that people are welcome to sit near me.”
B) “With my coat on, I am at a comfortable temperature as well as following the commonly accepted dress code inside a Catholic church.”
As an aside, a few weeks ago I discovered at the Latin Mass parish that wearing a mantilla while wearing a suede leather jacket just does not feel right and must have looked even worse

… Either the mantilla has to go (it can easily be replaced with a regular winter hat as a head covering), or the coat/jacket has to go and I take a chance on being cold.
As another aside, as an unmarried single conservative, I have in fact found in my experience that Protestants often treat me friendlier than Catholics do. The Lord has sent me a Methodist who considers me a best friend and another Methodist who considers me an adopted daughter, for example, and now another newer friend, also a Protestant. That said, at no time did I base the friendliness factor on whether or not someone was wearing a coat or not. The thought about coats never even crossed my mind.
~~ the phoenix