What does this say about those churches, though? If a religion can't instill good behaviour in its adherents, what use is it?I'm sorry, but people in churches are just people. You are going to find the same proportions inside the church as outside. Don't kid yourself.
I encourage you to go back and read the OP.
And in some cases, this could be a sign that the religion is flat-out wrong.
For instance, many Christian churches preach that once a believer accepts the Holy Spirit, the fact that they have the Holy Spirit dwelling in themselves will be expressed in their actions. If these Christians don't behave any better than some random non-Christian off the street, then this is a sign that they aren't actually saved or, potentially, that their whole religion is a lie.