I'm with lilypup, I hate FB and think it's really destructive for sensitive people, or people with self-esteem issues or people who feel like outsiders. I've seen to many people feel totally crushed by someone un-friending them in a snit. So ... I'd recommend that if FB is causing you distress that you get off it ... but, hey, I know that's unlikely. That just happens to be my standard rant. I hope you will at least consider it.

Now, to something more constructive and more likely. I don't know why people might be blocking you or unfriending you. If they're all from your church groups, it's likely that something happened that caused some sort of offense and it could be as ChipperMonkey said, that one person took offense at something and is blabbing to everyone else.

If this was happening to me, I'd go to the pastors of my church groups and ask for guidance. Maybe you're doing something that's violating the churches' doctrines or group norm. Maybe someone has just formed an unfair idea about you.

If many people in the church groups are excluding you, it really is the pastors' business. I hope you'll talk to them soon and really listen to their response if they tell you there's something you've done that violated church norms. Maybe you'll want to leave the groups, or maybe you'll want to correct your actions. Maybe the pastor will ask someone else to correct their actions. Or maybe people will be asked to remember the Golden Rule. There are many options available.

Talk to the pastor as soon as you can and listen with an open mind. I wish you the best.