There are three that testify:
References for 1 John 5:7
the Spirit and the water and the blood, and these three agree.
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.
References for 1 John 5:10
And this is the testimony: God gave us eternal life, and this life is in his Son.
Whoever has the Son has life; whoever does not have the Son of God does not have life.
I write these things to you who believe in the name of the Son of God, so that you may know that you have eternal life.
And this is the boldness we have in him, that if we ask anything according to his will, he hears us.
And if we know that he hears us in whatever we ask, we know that we have obtained the requests made of him.
If you see your brother or sister committing what is not a mortal sin, you will ask, and God will give life to such a one—to those whose sin is not mortal. There is sin that is mortal; I do not say that you should pray about that.
References for 1 John 5:16
All wrongdoing is sin, but there is sin that is not mortal.