God has the Word to speak for Him, and this Word is Christ. God has the only begotten Son as His speaking, the Word, to speak for Him and He also has the Spirit to bring forth the Word. When we speak the Word, the living Spirit goes along with our speaking. The Spirit accompanies the Word to bring the Word into people.
The coordination of the Word, God, and the Spirit is seen in the creation when Christ as the Word of God was creating by speaking (thus, the universe has been framed by the word of God—Heb. 11:3), and the Spirit of God was brooding (Gen. 1:2). Christ was speaking, "Let there be light." Then there was light. When Christ spoke, the Spirit was brooding.
In addition to the speaking of Christ as the Word in the five great historical events, Christ as the Word of God spoke for God by the prophets through His Spirit (1 Pet. 1:10-11). Christ as the Word of God speaks through the prophethood. When a particular point concerning Christ was conceived in a God-seeking person as a prophet, the Spirit of Christ brought forth the speaking of it through the prophet as the instrument. This was the way of the prophecy concerning Christ by the prophets in the Old Testament. In Luke 24:44 the Lord said, "All the things written in the Law of Moses and the Prophets and Psalms concerning Me must be fulfilled." The Law of Moses, the Prophets, and the Psalms are the three sections of the Old Testament. The Lord's word here indicates that the entire Old Testament is a revelation of Him and that He is its center and content.
In the Old Testament it was Christ as the Word of God, God Himself, and the speaking Spirit of God cooperating and coordinating in the speaking for God in the prophecies concerning Christ. This can be illustrated by Isaiah 7:14 concerning Christ being born of a virgin, Micah 5:2 concerning the birthplace of Christ, Daniel 9:26 concerning the time of the death of Christ, Malachi 4:2 concerning Christ's second appearing as the Sun of righteousness, etc. All these prophecies in the Old Testament are speaking Christ, and Christ is the totality of the Word of God. When the prophets speak Him, that means He speaks God.