Was Jesus created, or eternal? What was Arianism?

Theophilus of Antioch fl. c. 180 ADTo Autolycus 2.22

What is the voice but the Word of God, who is also his Son? Not as the poets and mythographers say, sons of gods born from intercourse, but as the truth relates: the Word, always present within God's heart. Before anything came to be he had him as counselor, being his own mind and understanding. When God wished to make what he had planned, he begot this Word, uttering him, the firstborn of all creation.

An early two-stage picture: the Word always within God, then uttered as Son for creation. Nicaea later avoided any "before" in God's begetting.

Origen of Alexandria c. 185–c. 254 ADOn First Principles 1.2.9

So another power comes to be, subsisting in its own nature, as Scripture says, "a breath of the power of God" (Wisdom 7:25), drawing what it is from there. But there is no time when it was not. If anyone wants to say that it did not exist before but came into being later, let him give the reason why the Father, who made it subsist, did not do so before.

A hundred years before Arius, Origen denies the very phrase Arius would use. Survives in Rufinus's Latin, which sometimes smooths Origen.

Arius (quoted by Athanasius) c. 256–336 ADThalia, quoted in Athanasius, Against the Arians 1.5

God was not always Father; there was a time when God was alone and was not yet Father. Later he became Father. The Son was not always. For all things came to be from nothing, and all are creatures and things made; so the Word of God himself came to be from nothing, and there was when he was not, and he was not before he came to be, but he too had a beginning of being created. For, he says, God was alone, and the Word and Wisdom did not yet exist. Then, wishing to create us, he made one being and named him Word and Wisdom and Son, so that he might create us through him.

The phrases Nicaea condemned. Arius taught that the Son was created before all ages, and that the Father alone is without beginning.

Council of NicaeaThe Creed of Nicaea, preserved in Socrates, Church History 1.8

We believe in one God, the Father Almighty, maker of all things visible and invisible; and in one Lord Jesus Christ, the Son of God, begotten of the Father, only-begotten, that is, from the substance of the Father, God from God, light from light, true God from true God, begotten, not made, of one substance with the Father ... But those who say "there was when he was not" and "before he was begotten he was not" and "he came to be from nothing" ... these the catholic Church anathematizes.

The creed of 325 with its anathema, as Eusebius sent it home to his church. The longer creed recited today is the revision of 381.