The word Trinity does not appear in the Bible. However, the doctrine is based on several emphatic assertions that are found throughout the biblical writings:

17 Jesus responded to them, “My Father is still working, and I am working also.” 18 This is why the Jews began trying all the more to kill him: Not only was he breaking the Sabbath, but he was even calling God his own Father, making himself equal to God.

19 Jesus replied, “Truly I tell you, the Son is not able to do anything on his own, but only what he sees the Father doing. For whatever the Father does, the Son likewise does these things. 20 For the Father loves the Son and shows him everything he is doing, and he will show him greater works than these so that you will be amazed. 21 And just as the Father raises the dead and gives them life, so the Son also gives life to whom he wants. 22 The Father, in fact, judges no one but has given all judgment to the Son, 23 so that all people may honor the Son just as they honor the Father. Anyone who does not honor the Son does not honor the Father who sent him.

24 “Truly I tell you, anyone who hears my word and believes him who sent me has eternal life and will not come under judgment but has passed from death to life.

25 “Truly I tell you, an hour is coming, and is now here, when the dead will hear the voice of the Son of God, and those who hear will live. 26 For just as the Father has life in himself, so also he has granted to the Son to have life in himself. 27 And he has granted him the right to pass judgment, because he is the Son of Man. 28 Do not be amazed at this, because a time is coming when all who are in the graves will hear his voice 29 and come out—those who have done good things, to the resurrection of life, but those who have done wicked things, to the resurrection of condemnation.

30 “I can do nothing on my own. I judge only as I hear, and my judgment is just, because I do not seek my own will, but the will of him who sent me.

31 “If I testify about myself, my testimony is not true. 32 There is another who testifies about me, and I know that the testimony he gives about me is true. 33 You sent messengers to John, and he testified to the truth. 34 I don’t receive human testimony, but I say these things so that you may be saved. 35 John, was a burning and shining lamp, and you were willing to rejoice for a while in his light.

36 “But I have a greater testimony than John’s because of the works that the Father has given me to accomplish. These very works I am doing testify about me that the Father has sent me. 37 The Father who sent me has himself testified about me. You have not heard his voice at any time, and you haven’t seen his form. 38 You don’t have his word residing in you, because you don’t believe the one he sent. 39 You pore over the Scriptures because you think you have eternal life in them, and yet they testify about me. 40 But you are not willing to come to me so that you may have life.

41 “I do not accept glory from people, 42 but I know you—that you have no love for God within you. 43 I have come in my Father’s name, and yet you don’t accept me. If someone else comes in his own name, you will accept him. 44 How can you believe, since you accept glory from one another but don’t seek the glory that comes from the only God? 45 Do not think that I will accuse you to the Father. Your accuser is Moses, on whom you have set your hope. 46 For if you believed Moses, you would believe me, because he wrote about me. 47 But if you don’t believe what he wrote, how will you believe my words?”