1st John only has 5 chapters, and 95 short verses.  Yet in this message, he use the word "know" 30 times, and the word "write" (declare, record) over 15 times.  He is saying that he is writing, declaring, recording everything down as a record.  He wants his first hand account to be preserved.

In 1:4, he says, "...these things have I written unto you that your joy may be full."  He wrote with a purpose in mind.  He knew that the truth of the message he had to tell us would fill our hearts with elation--because under the law, we were always under condemnation.  But now, once and for all our sins are forgiven.  Paid for.  We have eternal life.

He follows up in verse 5, "This then is the message which we have heard of Him, (Jesus) and that we declare (write) unto you..."  John wants to tell what he knows in a permanent form.  Writing.

John then gives a number of ways that you can know for sure that God lives in you.  Vs. 6 says that what we say is meaningless.  It is what we do that counts. "If we say that we have fellowship with him, and walk in darkness (sin), we lie..."  And in vs. 7 "If we walk in the light, we have fellowship one with another..."  We love our brothers in Christ.

Vs. 8-9 says, "If we say we have no sin...the truth is not in us...If we confess our sins...He will forgive and...cleanse us..."  John  is explaining what happens in our lives when we know Jesus.  We are changed.  We can examine ourselves for the proof of this change.  Saying?  Or doing.

Then in 2:1, John shows us his heart.  He calls us his little children--he wants to help us understand what we need to do.  "My little children, I am writing these things unto you that sin not..."

Finally John sums this all up by saying, "...hereby we know that we know him if we keep his commandments."  What are those commandments?  You can know you are a child of God if your desire is 1. To love the Lord your God with all your heart, mind and soul, and 2. Love your neighbor as yourself.  Jesus only gave us those two.

John writes to us because he wants us to be sure.  He wants us to know.