The Mormon Church stores a lot of sensitive data about you, e.g. your name, address, date of birth, telephone number. If you have children during the membership, also the names and birthdates of your children. Also church data such as baptism date, dates of temple ceremonies, attendance records are kept, members and missionaries are given your data to visit you and write letters. You are talked about in church meetings, how to bring you back to the church. When your children turn 8, the church will try to contact them to baptize your children.

The church keeps your data indefinitely. Even if you do not attend church for 20 years, you will still be listed as a member of the church. As long as you are listed as a member, the church also has a legitimation to contact you or, for example, to obtain information about you from residents' registration offices.

Even though you may have long since finished with the Church, you should still be aware that your name on the Church roll "stands as one of millions of witnesses to the truth of the Book of Mormon and the Church," as Church leaders like to put it.

The church has issued instructions on how parishioners should find out your address, etc. to contact you.

Here is a link to the church's English page, where they are listed.

It is described to go to your last known address and ask your neighbors if you no longer live there. One is to contact your friends and relatives to find out your current address if your phone number is incorrect, contact your phone provider and ask for the new number, write a letter to the old address and ask for the new address if you move, check with the registry office for your current address, search for you on Google, try to locate you on Facebook and social media, etc.