Berean Standard Bible (BSB)
Whoever believes in the Son of God has this testimony within him; whoever does not believe God has made Him out to be a liar, because he has not believed in the testimony that God has given about His Son.
World English Bible (WEB)
He who believes in the Son of God has the testimony in himself. He who doesn’t believe God has made him a liar, because he has not believed in the testimony that God has given concerning his Son.
Strong's King James
He that believeth{G4100}{(G5723)} on{G1519} the Son{G5207} of God{G2316} hath{G2192}{(G5719)} the witness{G3141} in{G1722} himself{G1438}: he that believeth{G4100}{(G5723)} not{G3361} God{G2316} hath made{G4160}{(G5758)} him{G846} a liar{G5583}; because{G3754} he believeth{G4100}{(G5758)} not{G3756}{G1519} the record{G3141} that{G3739} God{G2316} gave{G3140}{(G5758)} of{G4012} his{G846} Son{G5207}.
The F.O.G *
The one believing in the Son of the Elohim has the testimony in himself. The one not believing the Elohim has made Him a liar, because he has not believed in the testimony that the Elohim has given concerning His Son.
The F.O.G Message *
Anyone who continues to believe in Yahweh’s Son has the testimony within themselves. Anyone not trusting in Yahweh has made Him out to be a liar, for they don’t trust in the testimony that Yahweh has given about His Son.
Young's Literal Translation
He who is believing in the Son of God, hath the testimony in himself; he who is not believing God, a liar hath made Him, because he hath not believed in the testimony that God hath testified concerning His Son;