Wouldn’t it be uncharitable to exclude good people from your life, from friendship with you, simply because they aren’t Catholic? And wouldn’t that potentially be harmful in some ways? We all need good and true friends in our lives, and these might not always be people who share our faith.
We shouldn’t shun good, honest friendship because of differing religious beliefs. What if someone shunned YOU because you don’t believe as they do?
There’s too much of that kind of bigotry already in this country. Jesus says to love your neighbor as yourself. He never said to only love, and be friends with Catholics.
You could be causing yourself to miss out on some very warm and rewarding relationships by excluding from friendship those who aren’t Catholic.
I might also add that there’s no guarantee that people who share your faith will be good friends to you. They might turn their backs on you when you need them, even if they are also Catholics, whereas a non-Catholic friend might be there for you.