The Anchor Bible Dictionary, Ephesians 1-3, page 111 states,
“IN THE TALMUD tractate Pesachim 54a; cf. Nedarim 39b,seven things, i.e. the law, repentance, paradise, Gehinnom, the throne of glory, the heavenly sanctuary, and THE MESSIAH are not called pre-created, but pre-conceived in (God’s) thoughts.”
The ancient Jews during the time of Christ believed that the Messiah was “pre-conceived” in God’s expressed thoughts rather than literally existing as a timeless God the Messiah distinct from God the Father throughout eternity past. For God’s ability to preconceive and speak of the Messiah before his actual begetting was clearly explained by Paul in Romans 4:17 which states that God “calls the things which be not as though they were”. Thus we can understand why the apostle John, being a Jew, would have written that the word (logos = “expressed thought”) of God was with Him in John 1:1 and was later made flesh in John 1:14 to become the living Messiah who was “granted a life in himself” by his Father (John 5:26).
In Isaiah 37:26, Yahweh spoke His prophetic Word against Senacherib through Isaiah saying,
"Have you not heard? Long ago I did it, From ancient times I PLANNED IT. NOW I HAVE BROUGHT IT TO PASS that you (Senacherib) should turn fortified cities into ruinous heaps.
This is precisely what God meant in Isaiah 41:4,
“Who has performed and accomplished it, CALLING FORTH THE GENERATIONS FROM THE BEGINNING?”
Isaiah 37:26 clearly informs us that God already “did it” when He said, “I planned it” by speaking King Senacherib turning fortified cities into ruinous heaps. Likewise, the Scriptures clearly state that God already spoke His Word by “calling forth all (human) generations from the beginning (of creation – Ephesians 1:4)” before those human generations actual began. This explains why most of the Messianic prophecies were spoken by God as if the events in the life of the Messiah had already occurred when they were written. A prime example is found in Psalm 22 where it says, “They pierced my hands and my feet”.
Isaiah was very clear about the foreordained pre-conception of all things in the heavens and the earth before the heavens and the earth were actually created. For God said, “I WILL PLACE the Juniper in the desert together with the box tree and the cypress … the hand of Yahweh HAS DONE THIS and the Holy One of Israel HAS CREATED IT” (Isaiah 41:19-20). Notice that God said, “I WILL PLACE” trees in the desert in the future but then God goes on to say that He already “HAS DONE THIS and (already) … HAS CREATED IT” before He actually did it! Therefore we can rightly say that God had “pre-conceived” or “pre-created” all things in His own mind and plan before He actually created them. The same is true with God’s preconception about the Messiah within His own expressed plan before the Messiah had his actual beginning via his virgin conception and begetting.