Your statement is ridiculous. Try learning something about the Christian (Roman Catholic) tradition and worldview before arguing against some part of it. Ex-communication has existed since the beginning of the Church and is still a valid exercise of action by Church leadership where appropriate - whether you think it is stupid or not.

And, just so you know, most major Protestant churches also reserve the right to shun or kick out of their congregations anyone they find not upholding the standards of the faith (according to them).

And, btw, what you think is dumb is, I dare say, found in every religion to some extent. That is every religion has a means of dealing with heresy or rebelliousness against God's appointed authority.