9. If we accept [as we do] the testimony of men [if we are willing to take human authority], the testimony of God is greater (of stronger authority), for this is the testimony of God, even the witness which He has borne regarding His Son.
10. He who believes in the Son of God [who adheres to, trusts in, and relies on Him] has the testimony [possesses this divine attestation] within himself. He who does not believe God [in this way] has made Him out to be and represented Him as a liar, because he has not believed (put his faith in, adhered to, and relied on) the evidence (the testimony) that God has borne regarding His Son.
11. And this is that testimony (that evidence): God gave us eternal life, and this life is in His Son.
12. He who possesses the Son has that life; he who does not possess the Son of God does not have that life.
13. 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.