1. The witness of Jesus’ baptism
6 This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth. 7 For there are three that testify: 8 the Spirit and the water and the blood; and these three agree. 1 John 5:6-8 (ESV)

34 But one of the soldiers pierced his side with a spear, and at once there came out blood and water. 35 He who saw it has borne witness—his testimony is true, and he knows that he is telling the truth—that you also may believe. John 19:34-35 (ESV)

16 And when Jesus was baptized, immediately he went up from the water, and behold, the heavens were opened to him, and he saw the Spirit of God descending like a dove and coming to rest on him; 17 and behold, a voice from heaven said, “This is my beloved Son, with whom I am well pleased.” Matthew 3:16-17 (ESV)

2. The witness of Jesus crucifixion
6 This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth. 7 For there are three that testify: 8 the Spirit and the water and the blood; and these three agree. 1 John 5:6-8 (ESV)

13 But now in Christ Jesus you who once were far off have been brought near by the blood of Christ. Ephesians 2:13 (ESV)

3. The witness of the Holy Spirit
6 This is he who came by water and blood—Jesus Christ; not by the water only but by the water and the blood. And the Spirit is the one who testifies, because the Spirit is the truth. 7 For there are three that testify: 8 the Spirit and the water and the blood; and these three agree. 1 John 5:6-8 (ESV)

26 “But when the Helper comes, whom I will send to you from the Father, the Spirit of truth, who proceeds from the Father, he will bear witness about me. John 15:26 (ESV)

15 “A single witness shall not suffice against a person for any crime or for any wrong in connection with any offense that he has committed. Only on the evidence of two witnesses or of three witnesses shall a charge be established. Deuteronomy 19:15 (ESV)

14 He will glorify me, for he will take what is mine and declare it to you. John 16:14 (ESV)

4. The witness of the Father
9 If we receive the testimony of men, the testimony of God is greater, for this is the testimony of God that he has borne concerning his Son. 1 John 5:9 (ESV)

36   . . .  For the works that the Father has given me to accomplish, the very works that I am doing, bear witness about me that the Father has sent me. 37 And the Father who sent me has himself borne witness about me . . .   John 5:36-37 (ESV)

5. The witness of the faithful
10 Whoever believes in the Son of God has the testimony in himself. Whoever does not believe God has made him a liar, because he has not believed in the testimony that God has borne concerning his Son. 11 And this is the testimony, that God gave us eternal life, and this life is in his Son.
12 Whoever has the Son has life; whoever does not have the Son of God does not have life.
1 John 5:10-12 (ESV)