In this day and age letter writing might seem old fashioned and out of date, however it might be seen in a really good light.  How many times have you gotten a letter in the last year from friend or family?  Many be a few from people at Christmas.  Getting a letter is not something that is done much.  

Write out your testimony.  Make sure it included the fact that breaking God’s law will get us sent to hell.  Remember to include the fact that Jesus died on the cross, rose from the grave and assented into heaven 40 days later. It is important to explain that you repented and trusted Jesus.  By combining your testimony and the gospel you will have a powerful letter to send to a loved one.

If you want and example of this kind of testimony you can read mine.