If we [are willing to] accept the testimony of people about matters, [surely we ought to accept that] the testimony of God is more reliable; because the testimony of God is that He has presented [confirming] testimony concerning [the identity and mission of] His Son.

The person who [sincerely] believes in God's Son has the evidence [of it] within his heart, [confirming God's testimony]. The person who does not believe God [i.e., what He says about Jesus], accuses Him of lying, because he has not accepted the [irrefutable] testimony of God concerning [the identity and mission of] His Son.

And, moreover, we have learned to know, and have accepted as a fact, the love which God has for us. God is Love; and he who lives in love lives in God, and God in him.