Has the church been assigned to testify of God the Father or God the Son?
The Son of God is also known as the Word of God, word of the Lord, voice of the Lord, and the gospel that Abraham heard spoken to him. Those who testify to the Word of God ( Son of God ) that speaks words into their mind to write down or speak are called saints. A saint preaches the Word of God ( the Gospel ) to whoever the Father chose to listen to it and believe the words that they hear are coming from the Father, the Creator of everything.
Mark 1
14: Now after John was arrested,
Jesus came into Galilee, preaching the gospel of God,
15: and saying, "The time is fulfilled, and the kingdom of God is at hand; repent, and
believe in the gospel."
John 7
13: Yet for fear of the Jews no one spoke openly of him.
14: About the middle of the feast Jesus went up into the temple and taught.
15: The Jews marveled at it, saying, "How is it that this man has learning, when he has never studied?"
16: So
Jesus answered them, "My teaching is not mine, but his who sent me;
17: if any man's will is to do his will, he shall know whether the teaching is from God or whether I am speaking on my own authority.
18: He who speaks on his own authority seeks his own glory; but he who seeks the glory of him who sent him is true, and in him there is no falsehood.
John 12
49: For
I have not spoken on my own authority; the Father who sent me has himself given me commandment what to say and what to speak.
50: And I know that his commandment is eternal life.
What I say, therefore, I say as the Father has bidden me."
John 14
16: And
I will pray the Father, and he will give you another Counselor, to be with you for ever,
17:
even the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him; you know him, for he dwells with you, and will be in you.
23: Jesus answered him, "If a man loves me, he will keep my word, and my Father will love him, and we will come to him and make our home with him.
24: He who does not love me does not keep my words; and
the word which you hear is not mine but the Father's who sent me.
25: "These things I have spoken to you, while I am still with you.
26: But
the Counselor, the Holy Spirit, whom the Father will send in my name, he will teach you all things, and bring to your remembrance all that I have said to you.
1 John 2
27: but
the anointing which you received from him abides in you, and you have no need that any one should teach you; as his anointing teaches you about everything, and is true, and is no lie, just as it has taught you, abide in him.
Romans 10
8: But what does it say?
The word is near you, on your lips and in your heart (that is, the word of faith which we preach);
15: And
how can men preach unless they are sent? As it is written, "How beautiful are the feet of those who preach good news!"
16: But
they have not all obeyed the gospel; for Isaiah says, "Lord, who has believed what he has heard from us?"
17: So faith comes from what is heard, and what is heard comes by the preaching of Christ.
18: But
I ask, have they not heard? Indeed they have; for "Their voice has gone out to all the earth, and their words to the ends of the world."
John 5:
25: "Truly, truly, I say to you, the hour is coming, and now is, when
the dead will hear the voice of the Son of God, and those who hear will live.
26: For as the Father has life in himself, so he has granted the Son also to have life in himself,
27: and has given him authority to execute judgment, because he is the Son of man.
28: Do not marvel at this; for the hour is coming when all who are in the tombs will hear his voice.
37: And
the Father who sent me has himself borne witness to me. His voice you have never heard, his form you have never seen;
1 Thessolonians 14: For we know, brethren beloved by God, that he has chosen you;
5: for
our gospel came to you not only in word, but also in power and in the Holy Spirit and with full conviction. You know what kind of men we proved to be among you for your sake.
6: And you became imitators of us and of the Lord, for
you received the word in much affliction, with joy inspired by the Holy Spirit;
2 Timothy 2
7: Think over what I say, for
the Lord will grant you understanding in everything.
8: Remember Jesus Christ, risen from the dead, descended from David,
as preached in my gospel,
9: the gospel for which I am suffering and wearing fetters like a criminal. But
the word of God is not fettered.
John 1
1: In the beginning was the Word, and
the Word was with God, and the Word was God.
2: He was in the beginning with God;
3:
all things were made through him, and without him was not anything made that was made.
4:
In him was life, and the life was the light of men.
The flesh is not the Word of God. The words that Jesus and all other servants of God called prophets and saints that come from the Word of God is what gives life to all God's people and beasts. It's also known as the Breath of Life, or Tree of Life.
John 6
63:
It is the spirit that gives life, the flesh is of no avail; the words that I have spoken to you are spirit and life.