Thematic Bible: Who is true

So, Jesus answered them, "What I am teaching is not mine, but [it belongs] to Him who sent me [i.e., to God]. If anyone [really] desires to do what God wants, he will know whether my teaching comes from God or whether I am speaking on my own authority [only]. The person who speaks on his own authority is [just] trying to gain honor for himself. But the One who tries to gain honor from God, who sent Him, is [committed to] truth, and there is nothing false in His heart.

Now whoever has [a sufficient amount of] life's possessions and [then] observes one of his [Christian] brothers who does not have enough to get by on, but does not feel sorry for him [i.e., enough to help him out], surely a love for God does not continue to live in that person's heart. Little children [i.e., dear ones], we should not [merely] claim to love [people], or [even just] talk about it, but [we should love] by what we do [for them] in a genuine way. And this is how we will know that we are following [God's] truth, and will have assurance [of it] in our hearts and before God [as well]. read more.
But, if our hearts condemn us [for not demonstrating God's love for others], surely God, who is greater than our hearts [will also condemn us], because He knows all things. Loved ones, if our hearts do not condemn us [i.e., because we are showing love by helping the needy], we can have boldness before God [in prayer for our own needs];

Loved ones, do not believe [the message of] every spirit [i.e., every person claiming to be a teacher], but test the spirits [i.e., require proof that they and their message are genuine] to see whether they represent God [or not], because many false prophets have begun circulating throughout the world. Here is how to know [who is speaking from] the Holy Spirit of God: Every spirit [i.e., person] who proclaims that Jesus Christ has come [to earth] in a physical body is [speaking] from God. [See I Cor. 12:3].