We all like to be identified as belonging to a prestigious institution, for example: "I'm a Harvard Scholar you kneeeoooow", or "I belong to the Bent Iron Golf Club where Tiger Woods is a member you kneeeoooow".
And, why shouldn't we feel proud and boast about our exclusive memberships. It shows to others what we are.
We call this phenomenon "Honor by Association". And, you would generally expect to be identified by the rules and doctrines of these particular organisations. That is only fair and reasonable.
Church people who are elated by their faith will similarly feel proud to boast their association to their particular denomination: "I'm a Roman Catholic you kneeeoooow" or I'm a JW you kneeeoooow".
But then, if we look at the converse of Honor by Association, we have a phenomenon called "Guilt by Association".
For example: if you belonged to the KKK it would be reasonable and fair to label you as an extreme racist. Walk downtown in your hooded white gown and you will expect to get more than slightly criticised for being a disgusting racist. It just wouldn't make the cut if you tried to wriggle out of your association by saying, "oh no, I'm not racist, I don't go along with that horrible stuff, I am just a member because of the friendship and the cheap beer"
Similarly, isn't it the same with Church groups who are known for their bigotry, hatred and vilification of minority groups?
"Oh no, I am just a Catholic because I enjoy the fellowship and kneeling down, I don't go along with all that bigotry, hatred and vilification that all Christian Churches are known for"