I work for a company owned and run by Brethren - they are far and away the best employers I have ever had. Everything is really efficiently run and done by the book, they are extremely polite, kind and helpful and it is a very pleasant place to work. There are computers in the office, but there are super-stringent systems in place which block access to a lot of stuff on the internet. Certain access is allowed as a necessary part of running the operation, but nothing else. Which is fair enough really.
One day I happened to mention that it was a bit chilly in the office that day, and when I arrived at work the next morning they had put a little fan heater beside my desk. Very thoughtful and not an attitude I have ever encountere elsewhere!
They don't talk about themselves or their beliefs as such and although we chat about minor things in the office, they would no doubt be considerably more formal if we bumped into one another outside work. They don't socialise with people outside their faith, and eating is considered a social activity which is why the man was rather taken aback when you gave the invitiation to come round for coffee and cake. It is something that just isn't on their radar.
I sometimes take cakes into the office, and say that they are left over, and to please help themselves (I only work mornings and the cake is much appreciated, but eaten when I'm not there) 
They would probably be uncomfortable acccepting it as a gift though.
I once asked why they don't celebrate Christmas or Easter, and they said they didn't really know what they would do any differently to what they usually do any other day.
Each to their own I say.