This presumes a Bible-onlyist* methodology. Bible-onlyism is a difficult methodology to maintain since by definition it requires explicit statements of Scripture in order to validate any point of theology or practice; the problem is that Scripture itself doesn't:
A) Mention a Bible-onlyist methodology and
B) The very nature of the Canon of Scripture is the result of Christian Tradition. A product of what is, fundamentally, an apostate church in the minds of many. It therefore is somewhat amusing to those of us who confess the historic catholic and orthodox faith that those who are most antagonistic against said historic catholic faith use what is, fundamentally, a catholic collection of Scriptures. Whether one uses a Protestant, Roman Catholic, or Eastern Orthodox Bible it is, in essence, a catholic Bible.
Arius and the Arians believed there were two Gods. The Father who was uncreated, and the Son who was created. It is the Son who is the Creator of the heavens and the earth, the intermediary between the Father and creation; functioning similarly to the Demiurge in Platonic thought.
A common misconception about the Arians in modern times is that they were Unitarians, or that they believed Jesus to be only a human. They were neither, as the Creed of Ulfilias, an Arian bishop, attests:
"I, Ulfila, bishop and confessor, have always so believed, and in this, the one true faith, I make the journey to my Lord; I believe in one God the Father, the only unbegotten and invisible, and in his only-begotten son, our Lord and God, the designer and maker of all creation, having none other like him (so that one alone among all beings is God the Father, who is also the God of our God); and in one Holy Spirit, the illuminating and sanctifying power, as Christ said after his resurrection to his apostles: "And behold, I send the promise of my Father upon you; but tarry ye in the city of Jerusalem, until ye be clothed with power from on high" and again "But ye shall receive power, when the Holy Ghost is come upon you"; being neither God nor our God, but the minister of Christ ... subject and obedient in all things to the Son; and the Son, subject and obedient in all things to God who is his Father ... (whom) he ordained in the Holy Spirit through his Christ"
The ellipses the fragmentary nature of the surviving text.
The Arian teaching was that there was God (the Father) and God (the Son), God the Father created God the Son, and God the Son is "Lord and God, the designer and maker of all creation".
The controversy which resulted in Nicea was never about whether Jesus was God or not (all parties involved believed Jesus was God) but what was meant in calling Jesus God, the maker of all things; the Creed answers by saying He is homoousious, of the same substance, with the Father and therefore not a separate God from God the Father, and thus eternal, not created. He is, in the words of the Creed "God of God, Light of Light", "begotten, not made", "begotten before all ages". In the original Symbol of 325 the Creed asserts the important points being made, by denying those who would say that "there was a time when the Son was not". In the Symbol of 381 the anathemas are removed, but a more robust statement on the Holy Spirit is made in response to the Macedonians or Pneumatomachai--"those who war against the Spirit".
-CryptoLutheran
*Bible-onlyism as distinct from the historic Protestant concept of Sola Scriptura or Verbum Solum (Scripture alone and Word alone respectively) which state that Scripture exists as the final court of appeal, the norming norm, etc. Scripture Alone isn't Bible-onlyism, as Scripture alone does not say that there are is no authority or loci of theological importance outside of Scripture, but includes and assumes the importance of the Creeds and Confessions of the Church.