On that note, I don't know many closed-minded Christians. Sure, there are many caricatures and there's the Westboro baptist 'pseudo-church', but the closed-minded people I know are not in church. They're on facebook, telling the world how right they are.
Friendships change over time. It doesn't mean you have done anything wrong. It doesn't mean your friend has done anything wrong. Stop trying to figure out what you did wrong or blame the other person. Remember the friendship you once had as around memory.