The early churches believed that the Son was literally the Logos of God.
I apologize in advance for how difficult this subject is.
I've simplified this as much as I can. However, it's my job to report history, not make it up, and this part of history is difficult. Tertullian said so, and it is so.
I have made a page for you with an outline of the early Christian definition of the Trinity as taught by the Nicene Creed (and, as I hope to prove, by orthodox Christians prior to Nicea). That will be easier, but such a short summation can't really help you understand it.
What follows is not so difficult that it can't be understood! It just takes time and effort.
Not a lot of time and effort, just some.
You can do this!
I think that it's worth it for any Christian to know what the early church believed about the Trinity and what the Council of Nicea ratified.
Irenaeus (c. A.D. 185) begins his rule of faith by saying that the apostles and their disciples taught this. Why ignore it?
John 1:1 (with v. 14) teaches that the Son is the Word of God. However, today we neither understand that as fully nor take it as literally as the early churches did.
In Greek, "Word" is Logos, and it carries a much wider meaning than "word" does. It's the word from which we get "logic." The early churches were almost as prone to translating it "reason" as they were to translating it "word."
Here's Tertullian's very interesting explanation of what logos is:
Observe, then, that when you are silently conversing with yourself, this very process is carried on within you by your reason, which meets you with a word at every movement of your thought … Whatever you think, there is a word … You must speak it in your mind …
Thus, in a certain sense, the word is a second person within you, through which in thinking you utter speech … The word is itself a different thing from yourself. Now how much more fully is all this transacted in God, whose image and likeness you are? (ibid. 5)
Logos is that voice you hear inside yourself when you are thinking. At least, that's a rough estimation of what logos means. Tertullian goes out of his way to describe it as "a second person within you" because he's bringing up the Logos of God as a second Person of the Trinity.
God, according to the early churches, has always had logos inside of him.
According to the early Church, there was a time when the Logos of God was inside of God. In fact, God was not yet the Father, nor yet was there a Trinity. He was simply the one God, because he had not yet begotten the Son.
Right here it's very important to note that thinkers like Clement of Alexandria (c. A.D. 190) and his student Origen would adjust my "not yet." They would say that because the birth of the Logos of God happened in eternity past, then it had always happened.
Though Tertullian says there was a time when God was alone, Clement and Origen would say there was no time then. What happened in eternity past had always happened.
It appears to me that most early Christians weren't that philosophical, and they just saw it Tertullian's way … if they could understand it at all.
Before all things God was alone … He was alone because there was nothing external to him but himself. Yet even then was he not alone, for he had with him that which he possessed in himself—that is to say, his own Reason.
… Although God had not yet sent out his Word, he still had him within himself …
I may therefore without rashness establish that even then, before the creation of the universe, God was not alone, since he had within himself both Reason, and, inherent in Reason, his Word, which he made second to himself by agitating it within Himself. (ibid. 6)
In other words, there was a time when the Logos of God was inside of God. God was alone, but he had fellowship with his own Logos inside of him. When it was time to create the world, it was then that God birthed the Word as the second person of the Trinity:
Now as soon as it pleased God, he first put forth the Word … in order that all things might be made through him. (ibid.)
You can probably see that if this is the view of the Trinity taught by the early church, it would be easy for Arius to conclude "there was a time when the Son did not exist."
The early church answer was that there was a time when the Son was not separate from the Father, but there was never a time when he didn't exist. Before he was separate from the Father, he was already the Logos inside of God.
Don't miss that last paragraph. That statement is what the Council of Nicea was about.
It's common to teach now that the Council of Nicea was about whether Jesus was God. That is only true if you understand the early Church view of the Logos of God.
The Council of Nicea convened to determine whether, in the beginning, God created the Son by emitting his own Logos or whether he formed him from nothing the way he created everything else. They were not afraid to use the term "created" because Proverbs 8:22 used it.
There was a term for this important issue: homoousios. It was so important that it was inserted in the Nicene Creed twice.