There's a lot of searching on the net (no specifics now) you can do to see the other side of the Arian contraversy. Arians were quite guilty of the same, spreading lies concerning the clergy etc..
Howbeit, I feel that the 4th century had little to do with the "formation" of the Trinity. Read the early church fathers (50-200AD) and you'll see they were closer to Trinitarians than anything. ;)
100 AD Ignatius of Antioch 100 AD Ignatius of Antioch "We have also a Physician the Lord our God, Jesus Christ, the only-begotten
Son and Word, before time began, but who afterwards became also man, of Mary the virgin." (Letter to the Ephesians.) 100 AD Ignatius of Antioch "Ignatius, who is also Theophorus, unto her that hath found mercy in the bountifulness of the Father Most High and of Jesus Christ His only Son; to the church that is beloved and enlightened through the will of Him who willed all things that are, by faith and love towards Jesus Christ our God
; even unto her that hath the presidency in the country of the region of the Romans..." (Letter to the Romans 1) 100 AD Ignatius of Antioch "Nothing visible is good. For our God Jesus Christ
, being in the Father, is the more plainly visible. The Work is not of persuasiveness, but Christianity is a thing of might, whensoever it is hated by the world." (Letter to the Romans) 100 AD Ignatius of Antioch "I give glory to Jesus Christ the God
who bestowed such wisdom upon you" (Letter to the Smyraeans ) 100 AD Ignatius of Antioch "Jesus Christ . . . was with the Father before the beginning of time
, and in the end was revealed. . . . Jesus Christ . . . came forth from one Father and is with and has gone to one [Father]. . .. [T]here is one God, who has manifested himself by Jesus Christ his Son, who is his eternal Word, not proceeding forth from silence, and who in all things pleased him that sent him" (Letter to the Magnesians 6-8). 100 AD Ignatius of Antioch "Ignatius, also called Theophorus, to the Church at Ephesus in Asia . . . predestined from eternity for a glory that is lasting and unchanging, united and chosen through true suffering by the will of the Father and Jesus Christ our God
" (Letter to the Ephesians 1). 100 AD Ignatius of Antioch " For our God, Jesus Christ
, was conceived by Mary in accord with God's plan: of the seed of David, it is true, but also of the Holy Spirit" (Letter to the Ephesians, 18:2). 100 AD Ignatius of Antioch "[T]o the Church beloved and enlightened after the love of Jesus Christ, our God
, by the will of him that has willed everything which is" (Letter to the Romans 1). 100 AD Ignatius of Antioch "There is then one God and Father, and not two or three; One who is; and there is no other besides Him, the only true [God]. For "the Lord thy God," saith [the Scripture], "is one Lord." And again, "Hath not one God created us? Have we not all one Father? And there is also one Son, God the Word. For "the only-begotten Son," saith [the Scripture], "who is in the bosom of the Father." And again, "One Lord Jesus Christ." And in another place, "What is His name, or what His Son's name, that we may know? " And there is also one Paraclete. For "there is also," saith [the Scripture], "one Spirit," since "we have been called in one hope of our calling." And again, "We have drunk of one Spirit," with what follows. And it is manifest that all these gifts [possessed by believers] "worketh one and the self-same Spirit." There are not then either three Fathers, or three Sons, or three Paracletes, but one Father, and one Son, and one Paraclete. Wherefore also the Lord, when He sent forth the apostles to make disciples of all nations, commanded them to "baptize in the name of the Father, and of the Son, and of the Holy Ghost," not unto one [person] having three names, nor into three [persons] who became incarnate, but into three possessed of equal honour."
(Letter to the Philadelphians 2).
As you noted, Rubenstein is neither a biblical scholar nor a theologian. You can see a review of his book here:
...where a noted Trinitarian apologists confirms it's nature and actually suggests reading it.