Our Scripture reading today is 1 John 5:11-13.
Verse 13, "These things have I written unto you that believe on the name of the Son of God; that ye may know that ye have eternal life, and that ye may believe on the name of the Son of God."
There are many different Biblical truths that we need to know.  We need to know that God loves us. (John 3:16; 1 John 4:8)  We need to know that God is always able.  (2 Timothy 1:12, Hebrews 7:25). In order to live in daily victory, we must know that we have eternal life.  The word "know" in verse 13 means to perceive, to see, to be aware.  The Lord Jesus Christ death, burial and resurrection provided any and all repentant sinners with eternal life.  By putting our faith in Him we are no longer condemned to Hell.  John 3:18, "He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God."
A child of God knows they have eternal life by spending time in His Word.  Look again at the first statement of verse 13, "These things have I written unto you..."  Please allow that to settle into your heart.  The Word of God was written for and to YOU!  It is a personal letter of love from the Creator God to you and me.  Isn't that amazing?  One of, if not the most important Bible doctrine to know is eternal security.  A born again child of God cannot lose his or her salvation.  We know this because of the Word of God. (John 3:16; 5:24; 10:27-29, etc...)
Do you know that you are saved and have eternal life?