This verse is a transition between verses 6-12 and 14-17.  After John ends his thoughts about the threefold witness of Christ’s identity in verses 6-12 by explaining that those who have the Son have eternal life, he summarizes that idea with this verse.  Then he begins a new thought in verse 14 about the confidence in prayer that comes from belief in the Son and the possession of eternal life.

Background
This is the sixth and final time that John tells his readers why he has written this letter.  It is interesting that John does this so many times.  He realizes he is writing to people who need to be both taught and reassured, and part of that is to repeatedly remind them why he writes.  While each of his explanations emphasizes a vital facet of his teaching, it is probably not too much of a stretch to say the first and the last – because of their positions – are the key purposes of the letter and the ones he most wants to emphasize.

The first explanation is in 1:1-4 where John says he writes so his and the apostles’ joy will be complete.  Their joy comes from proclaiming the life and work of Jesus (who he calls the Word of Life and the eternal life which was with the Father) – the gospel – so others can share in the fellowship they enjoy with the Father and the Son.  Personal fellowship and communion with God are possible because of the appearance of the Son.

Thus John bookends his letter by telling his readers they can have fellowship with God through the Son in 1:4 and that they can know they have eternal life through the Son in 5:13.  These promises, while stated differently, are really much the same.  In His high priestly prayer in John 17 Jesus said, “And this is eternal life, that they may know You, the only true God, and Jesus Christ whom You have sent” (17:3).  Jesus says eternal life consists of knowing the Father and knowing the Son.  The fellowship with God that John invites his readers to share with him in the beginning of the letter IS eternal life.  When we know God we fellowship with Him, which is a picture of the eternity we will spend with Him.  Fellowship and eternal life are really two aspects of the same truth – Jesus enables us to have a relationship with God that never ends.  And we can be sure we have this relationship when we believe in the Son.  John begins and ends his letter with the promise of eternity for those who believe.

Explanation
John writes this verse to those who believe in the name of the Son of God.  It is only believers who can know – thus only those assured of their belief will have assurance of their eternity.  Remember that throughout this letter he has repeated three requirements for the assurance of belief: obedience to God’s commands, love for God and others, and faith in Jesus (summarized in 3:23-24, 5:1-5).  Without these three it is impossible to claim belief.  One who does not practice righteousness or one who does not love his brother (and God) or one who does not understand who Jesus is cannot claim to be a believer and so cannot know he has eternal life.  The one who believes in the Son of God has eternal life and the one who as a result of belief practices righteousness and loves his brothers knows he has eternal life.

So the one who can claim this verse has certain characteristics:

• He is born of God through belief that Jesus is the Christ (5:1).
• He overcomes the world through his belief (4:4, 5:4-5)
• He does not love the world (2:15-17)
• He loves God by obeying His commands (5:2)
• He does not practice sin (3:8)
• He loves others (4:7,21)
• He knows he loves God because he loves others (4:20)
• He knows he loves others because he loves God (5:2)

The NOW
Just like in verses 11 and 12 John uses the present tense to explain this promise.  He does not say those who believe WILL have eternal life – he says they HAVE eternal life.  God does more than legally justify us when we are saved; He invites us into relationship in this life.  And this relationship is a slice of the relationship we will someday enjoy on the new earth.  It will then be unaffected by sin and in His physical presence – but it will not be any more real or everlasting.  Eternity is perfect communion with God in His physical presence in a perfect world forever.  What we have now is communion with God in His presence in a sin-drenched world for as long as we live.  It is not perfect but it is NOW.  And though we cannot see the throne of God as we someday will, we have unfettered access to it NOW.

There are really two elements to the present tense aspect of this assurance.  The promise of the future is so certain that we can confidently claim it now – and the Son’s appearance in our world enables us bold access to the throne now.  We claim it now and we experience it now.

This is another example of the principle of “already and not yet” that we see throughout the New Testament.  The kingdom of God is realized now through the person and work of Christ but there is an element to it that will not be fully realized until the consummation of the age.  Jesus ushered in the kingdom and we have fellowship with the Father and communion through His Spirit – but the ultimate realization of that communion will come on the new earth.  We experience the kingdom of God now and we experience eternal life now but the full consummation of both is yet to come – they are “already and not yet.”

The KNOW
Maybe even more exciting than the ‘now’ element to this verse is the ‘know’.  John says he writes that we may KNOW.  Not hope, not wish, not assume – KNOW.  Two things separate Christianity from any other religion – Christians do not work their way to heaven and Christians are certain OF heaven.  We do not guess and we do not have to go through life wondering.  Jesus paid the whole price and justified us fully and His resurrection guarantees that we who are His will be with Him eternally.

What a gift that God allows us to know!  The good news of the gospel is that through no effort of our own we have a way out of the hopelessness of sin.  Jesus paid our debt and in so doing enabled us to be justified before the Holy Judge of the world.  Even more, we are granted the privileges of sonship that allow us to live in relationship with that same Judge immediately.  And even more than that, we have the promise of someday spending eternity in His presence in a perfect world He designed for us.  But that is still not everything!  He then gave us His word so we can KNOW this gift exists!!  He paid it all so He can promise it all and we can receive it all and know we received it.  WE GET TO KNOW!  WE GET TO KNOW!  WE GET TO KNOW!  This is the essence of the Christian life, that we might have the full knowledge of God and that we may know we have it. (D. Martyn Lloyd-Jones, Life in Christ; 556.)  As it is used here, is there a better word in our language than KNOW?

Thought: If John writes so we can know, what does it mean when we doubt?  Or said another way, is it ever OK not to know?  Both Paul and Peter seem to speak to this when they admonish their readers to examine themselves to make sure they are in the faith (II Cor 13:5, II Pet 1:10-11).  If we are to examine ourselves, it follows that times of reflection and doubt are not out of the question.  One of the deceptions of the Enemy is to tell us that testing ourselves shows a lack of faith – that we doubt God and sin against Him when we set out to make our calling sure.  But this only maintains the deception of one who may not truly be saved.  Times of reflection are healthy and times of doubt are human nature – as long as we come back to the gospel and use our doubt to make sure our hope is in Christ alone and our lives reflect our belief, we can profit from the test.

On the other hand, one who continually doubts brings into question the efficacy of Jesus’ sacrifice and promises.  If there is always doubt then apparently Jesus is not enough.  And one who is never sure of his calling is either involved in long-term sin or has a view of God that assumes God is always on the lookout for someone to suffer His wrath.  In either case, the belief of one like this is seriously in question.  The one who has a wrong view of God or whose life is marked by the practice of sin has no claim on the assurance John promises.  The Christian knows even if that knowledge is not perfect or continual.  There is a difference between an unrenewed mind and a never-renewed mind.

Implications
Knowing I have eternal life means:

• I purify myself in the expectation of seeing Jesus and being with Him. Since He is pure I want to be pure (3:3).  The knowledge of eternal life does not give me license to live however I want but inspires me to live with eternal values now (II Cor 7:1).  I live always with the thought that I will someday be with Him and be like Him.

• I do not love the world. The things of the world are the lust of the flesh and the lust of the eyes and the boastful pride of life (2:16).  What place do those things have in my life when they are contrary to the eternity I know I have?

• I do not heap up treasures on this earth. If I KNOW eternal treasures are waiting for me and if I am experiencing a taste of eternity NOW – what purpose do temporal treasures and gain play in my life?  What is the point of worldly wealth if it takes my focus off of the wealth of the world I KNOW is mine?  Along this same line – why would I covet?  What could I possibly want from this world that is anywhere near what is promised to me in the next?

• I have fewer expectations of this world and this life. I do not expect this life to measure up to eternal life.  I do not expect this world to measure up to paradise.  Since I know I have paradise I am willing to accept that I will not always be happy or prosperous or healthy this side of it.  This life is not all there is so I do not expect it to ultimately satisfy or ultimately please.

• I look at people differently. Do I have a difficult or disappointing child?  I have eternal life.  Do I have a difficult or disappointing spouse?  I have eternal life.  Do I have a difficult or disappointing boss?  I have eternal life.  Are people continually letting me down and continually causing me anxiety and worry and heartbreak?  I have eternal life!  Just as I have fewer expectations of the world I have fewer expectations of people.  I do not require them to fulfill me or encourage me or affirm me.  I have an eternal relationship with my heavenly Father wherein I find my encouragement and satisfaction.  And I have the promise of a new world with multitudes of people no longer living with the ramifications of sin – and I can wait for that day and not expect it from those I am with now because I KNOW it is coming.

• I have hope in the midst of trials. I may not know why God puts me through what He puts me through and I may not agree that the tough times God sends my way are fair or needed.  But nothing has to make sense in this life if I know I have eternal life with Him.  I do not demand answers or fairness when I know eternity is coming which remedies all injustice and eradicates all traces of sin.  It may be that God puts me into a vise so tight that I can no longer tell which way is up or who is a friend and who is an enemy.  But I know I will always be able to claim John’s promise and I will always have the ultimate trump card.  It may be dark, but I have eternal life.  I may be lost or drowning, but I have eternal life.  I may be broke, unemployed, or dying – but I have eternal life.

I know not what of good or ill
May be reserved for me,
Of weary ways or golden days,
Before His face I see.

But I know Whom I have believèd,
And am persuaded that He is able
To keep that which I’ve committed
Unto Him against that day.

To have eternal life means, as John has reminded us in the third chapter, that I shall see God.  If I have this life, I shall see Him; I shall see Christ as He is, and I shall stand in His presence.  It is only those who have His nature and share His life and who have been born again who will go on to that; and those who have it will see Him and will be like Him, and they will spend their eternity in glory with Him, enjoying it in His glorious presence.  (D Martyn Lloyd-Jones, Life in Christ; 559.)