The one who believes in the Son of God [who adheres to, trusts in, and relies confidently on Him as Savior] has the testimony within himself [because he can speak authoritatively about Christ from his own personal experience]. The one who does not believe God [in this way] has made Him [out to be] a liar, because he has not believed in the evidence that God has given regarding His Son. And the testimony is this: God has given us eternal life [we already possess it], and this life is in His Son [resulting in our spiritual completeness, and eternal companionship with Him]. He who has the Son [by accepting Him as Lord and Savior] has the life [that is eternal]; he who does not have the Son of God [by personal faith] does not have the life. These things I have written to you who believe in the name of the Son of God [which represents all that Jesus Christ is and does], so that you will know [with settled and absolute knowledge] that you [already] have eternal life. -1 John‬ ‭5:10-13‬ (amp)

The one who believes… (adheres to, trusts in, and relies confidently on Him as Savior…

We are eternal. Because we have a Savior who conquered death… And because of Christ we can know (with settled and absolute knowledge) that we (already) have eternal life. Is this not wonderful news?!?!? This world will die out and so will the things of this world, but we are His. Believe it, rely on it, live it.