If we receive human testimony, the testimony of God is greater; for this is the testimony of God that he has testified to his Son. Those who believe in the Son of God have the testimony in their hearts. Those who do not believe in God have made him a liar by not believing in the testimony that God has given concerning his Son.
1 John 5:9-10, NRSV
One day when I was walking my dog, I saw this graffiti on one of the back alley walls that says: "Truth is relative." In another word, there is no false as long as someone believes something is true. This statement looks inclusive enough for today's climate of pro-politically correctness. But I would argue that this idea itself is a false statement, and I would use some more extreme examples to prove it. If this statement is true, the discipline of psychology and psychiatry are no longer needed in medicine. Their so called "patients" should accept that every "illusions" and "voices" they see and hear are authentic. Becuase no matter whatever causes them to see and hear the none-existences, the images and sounds are real to them according to them. (relative) I don't think there is any need to explain the danger of this idea further.
On another hand, it feels like that it's getting harder to find out whether a person is speaking the truth. Sadly in real life, we have not much choice but to rely on people to be honest most of the time. The passage today says that if we even believe the testimony of a human being, we should trust in God more. God has testified for His Son Jesus Christ in His follower's hearts with the out pouring of the Holy Spirit. Anyone who doesn't believe in Jesus Christ is basically proclaiming God as a liar. This includes all the heresies that declare that Jesus Christ is not the savior, not the only savior, or not enough to be the savior alone.
Have you met any habitual liar before? Do you have any experience of how dishonest a person could be? Pray for your partner that you'll each live out an honest life that testifies for Jesus Christ. Also, pray for each other to have the wisdom to separate the false teachings from the orthodox teachings.