It provides them with a moral compass for life. It gives them a religious inheritance to pass on to their children. It provides them with a road map from earth to heaven. The truth is there are no churches whose members are sinless. If that's what you're looking for, you won't find it.
Church members make mistakes and have faults.
Don't put your faith and trust in people. That should be reserved only for God. People can and do let us down. One of the principal teachings of the New Testament is forgiveness. If we want to receive forgiveness for our sins, we have to forgive others theirs.