Word of God I?
Gospels!
Luke 4:4  And Jesus answered him, saying, It is written, That man shall not live by bread alone, but by every word of God.
Luke 8:11  Now the parable is this: The seed is the word of God.
Luke 11:28  But he said, Yea rather, blessed are they that hear the word of God, and keep it.

Word of God II?
Acts!
Acts 23:11  And the night following the Lord stood by him, and said, Be of good cheer, Paul: for as thou hast testified of me in Jerusalem, so must thou bear witness also at Rome.
Acts 27:23,24  For there stood by me this night the angel of God, whose I am, and whom I serve,  Saying, Fear not, Paul; thou must be brought before Caesar: and, lo, God hath given thee all them that sail with thee.

Word of God III?
Pauline Epistles!
Romans 10:17  So then faith cometh by hearing, and hearing by the word of God.
Ephesians 6:17  And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
I Thessalonians 2:13  For this cause also thank we God without ceasing, because, when ye received the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe.

Word of God IV?
Christ Himself!
Gospels
John 1:1,14  In the beginning was the Word, and the Word was with God, and the Word was God.  ...  And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
Revelation 19:13  And he was clothed with a vesture dipped in blood: and his name is called The Word of God.

II.  ... it can't only be the Book of Acts!
They had no complete Bible - Christ Himself along with the Holy Spirit made direct contact with Paul - We Don't today!  (and it certainly isn't Acts 2:17,18)
Acts 10:19  While Peter thought on the vision, the Spirit said unto him, Behold, three men seek thee.
Acts 11:12  And the Spirit bade me go with them, nothing doubting. Moreover these six brethren accompanied me, and we entered into the man's house:
Acts 16:7  After they were come to Mysia, they assayed to go into Bithynia: but the Spirit suffered them not.
Acts 21:4  And finding disciples, we tarried there seven days: who said to Paul through the Spirit, that he should not go up to Jerusalem.

III.  ...could it be the entire Written Bible? - the King James Bible - More on this one in the sermon.

IV.  ... It can't be only Christ Himself today!
He hasn't come yet, so if that were to be the belief, wouldn't we suppose that we should be doing all that took place in Acts - even by Paul himself.

note:
Some folks think that Paul preaching the Kingdom of God even in Acts throws a kink into the thought about Preaching Paul and the KJB in I Corinthians 13:10. and throwing out baptism, Lord's Supper, laying on of hands, healing, tongues, etc.  For example: Paul healed and did the snake thing even while preaching the Kingdom of God in late Acts 28.
Acts 19:8  And he went into the synagogue, and spake boldly for the space of three months, disputing and persuading the things concerning the kingdom of God.

And there is more Kingdom of God in Acts:
Acts 20:25  And now, behold, I know that ye all, among whom I have gone preaching the kingdom of God, shall see my face no more.
Acts 28:23,31   And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening. ... reaching the kingdom of God, and teaching those things which concern the Lord Jesus Christ, with all confidence, no man forbidding him.
Also see Acts 8:12 - Philip  But when they believed Philip preaching the things concerning the kingdom of God, and the name of Jesus Christ, they were baptized, both men and women. (note what happens around that verse?)
Acts 14:22   Confirming the souls of the disciples, and exhorting them to continue in the faith, and that we must through much tribulation enter into the kingdom of God.
Even Jesus did it in Acts 1:3  To whom also he shewed himself alive after his passion by many infallible proofs, being seen of them forty days, and speaking of the things pertaining to the kingdom of God:

Is this a problem?  No, not at all!

see II Chronicles 8:16 for Biblical use of perfect - finished / completed.
a.  Christ is not yet completed.
b.  The Book is completed / finished.  Psalm 12:6,7

Listen to explanation on the audio sermon:

For we know in part, and we prophesy in part.
That was in Paul's time - they only knew and prophesied what Christ / Spirit of God would tell them!

But when that which is perfect is come, then that which is in part shall be done away.
When the Scriptures arrived on the scene, then everything was placed on and in those Scriptures!

When I was a child, I spake as a child, I understood as a child, I thought as a child: but when I became a man, I put away childish things.
We grow up when we read this Book (Ephesians 4:14- That we henceforth be no more children, tossed to and fro, and carried about with every wind of doctrine, by the sleight of men, and cunning craftiness, whereby they lie in wait to deceive) and learn the correct doctrines, correction and instruction of righteousness, etc.

For now we see through a glass, darkly; but then face to face:
Hebrews 4:13 explains this verse. The people then didn't see anything clearly as we can do today, yet we still can be 'face to face' with Christ, however only in a  Spiritual sense - this is 100% the Kingdom of God!

The physical Christ will be for the physical kingdom ... John 18:36  Jesus answered, My kingdom is not of this world: if my kingdom were of this world, then would my servants fight, that I should not be delivered to the Jews: but now is my kingdom not from hence. ... will come in Revelation 19!

now I know in part; but then shall I know even as also I am known.
That Book has us pegged, again, see Hebrews 4:12,13 - all we have to do is to get into it!

And now abideth faith, hope, charity, these three; but the greatest of these is charity.  This was BEFORE the written Scriptures.  Now we get HIS faith, our hope in a REAL CHRIST and even how to have charity (not love) from the Scriptures themselves...