What is the purpose of writing a letter from the sender to the receiver. It is to convey a message from a person to another person. The contents of a letter can be expressing an opinion, suggestion, personal experience, speech, report of observations, instructions or expression of love and many other things too.
In the Bible, we have a collection of letters that—thanks to the inspiration and guidance of the Holy Spirit—have made their way through time to us. As the Christian church grew, Jesus’ disciples wrote to local churches across Europe and Asia Minor to help the people understand their new life in Christ; many of those letters were collected in the Bible we read today.
What did these letter-writers want to convey to readers? John explains, in his first letter, that he’s writing about “that which was from the beginning, which we have heard, which we have seen with our eyes, which we have looked at and our hands have touched.” He’s writing about his encounter with the living Christ (1 John 1:1). He writes so that his readers may “have fellowship with” one another, and with “the Father and with his Son, Jesus Christ” (v. 3). When we have fellowship together, he writes, our joy will be complete (v. 4). The letters in the Bible draw us into a fellowship that’s beyond time—fellowship with the eternal God. If I wrote a letter to a friend telling about how I’ve encountered the living God, I would tell my friend how I changed from the personality I was and became what I am today and made a comparison.