I write these things to you who believe in the name of the Son of God so that you may know that you have eternal life.
NIV
I write this to you who believe in (adhere to, trust in, and rely on) the name of the Son of God [in the peculiar services and blessings conferred by Him on men], so that you may know [with settled and absolute knowledge] that you [already] have life, yes, eternal life.
AMP
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.
KJV
This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us.
NIV
And this is the confidence (the assurance, the privilege of boldness) which we have in Him: [we are sure] that if we ask anything (make any request) according to His will (in agreement with His own plan), He listens to and hears us.
AMP
And this is the confidence that we have in him, that, if we ask any thing according to his will, he heareth us:
KJV
Everyone who believes that Jesus is the Messiah is born of God, and everyone who loves the father loves his child as well.
NIV
EVERYONE WHO believes (adheres to, trusts, and relies on the fact) that Jesus is the Christ (the Messiah) is a born-again child of God; and everyone who loves the Father also loves the one born of Him (His offspring).
AMP
Whosoever believeth that Jesus is the Christ is born of God: and every one that loveth him that begat loveth him also that is begotten of him.
KJV
The Spirit, the water and the blood; and the three are in agreement.
NIV
And there are three witnesses on the earth: the Spirit, the water, and the blood; and these three agree [are in unison; their testimony coincides].
AMP
And there are three that bear witness in earth, the Spirit, and the water, and the blood: and these three agree in one.
KJV
In fact, this is love for God: to keep his commands. And his commands are not burdensome
NIV
For the [true] love of God is this: that we do His commands [keep His ordinances and are mindful of His precepts and teaching]. And these orders of His are not irksome (burdensome, oppressive, or grievous).
AMP
For this is the love of God, that we keep his commandments: and his commandments are not grievous.
KJV
We know also that the Son of God has come and has given us understanding, so that we may know him who is true. And we are in him who is true by being in his Son Jesus Christ. He is the true God and eternal life.
NIV
And we [have seen and] know [positively] that the Son of God has [actually] come to this world and has given us understanding and insight [progressively] to perceive (recognize) and come to know better and more clearly Him Who is true; and we are in Him Who is true--in His Son Jesus Christ (the Messiah). This [Man] is the true God and Life eternal.
AMP
And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.
KJV