Unfortunately, doing church properly tends to be a messy business, where you meet all kinds of people with all manner of hangups, problems and besetting sins. A church that doesnt let sinners through its doors is going to be very empty.
The Church obviously is made up of sinners - we all fall short of the Glory of God. That being said, a Church that permits someone to attend that has ongoing sin issues should first confront that person and if it continues bring it before the Church. This is clearly taught in Matthew 18. If that person persists in that sin he is to be disfellowshipped. This church obviously does not follow Scriptural prescription in this instance.