Oh Arius, you Darnel!

But while his men were sleeping, his enemy came and sowed tares among the wheat, and went away.
Matthew 13:25 

Arianism was among the major issues discussed at the Council of Nicaea in 325. At that time there was no commonly adopted doctrine about anything in the Kingdom of God. Persecuted Christians did not have the chance to come together to talk about the content of their faith. The Scriptures were a gentle guide drawing the line between Judaism, Christianity and paganism but as we know, they raise as many questions as they answer.
Constantine I had learned to his dismay that bitter disputes existed among the Christians also about the most fundamental issues, such as Who is God. How could such a confused religion unite the people of the Empire under One God and one Caesar?

Theologians had written many treaties that tried to solve the breaking up of the theological concept of One God of Israel because of what had happened in Jesus Christ. Some of them were working on the line that was eventually accepted at Nicaea: God is One Trinity. This paradoxical close-up of One God has ever since been the fundamental teaching of Christian churches.

Trinity
The concept of Trinity is not really clear in the classic wording of the Nicene Creed:

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 [the only-begotten; that is, of the essence of the Father, God of God], 
Light of Light, 
very God of very God, 
begotten, not made, 
being of one substance with the Father;
By whom all things were made [both in heaven and on earth];
Who for us men, and for our salvation, came down and was incarnate and was made man;
He suffered, and the third day he rose again, ascended into heaven;
From thence he shall come to judge the quick and the dead.
And in the Holy Ghost.

Faith in One God, Monotheism, the pillar of Judaism (Shema Israel) and absolute foundation of Islam.

They have it easy.

The section on Lord Jesus Christ is highly complex language and difficult to understand, at the limits of what human languages - even the delicate classical Greek - can express.


Arianism
In the Kingdom of Heaven there was a more sensible solution proposed by presbyter Arius (250–336) from the theological capital of Alexandria.

Faith in One God.

This must be the unshakeable foundation of true faith.

So why let this Jesus guy, admittedly a human born in the little town of Bethlehem, to break up this teaching of the One Majesty, God of Israel?

Arius relied on the holy Scriptures that underline that God is One and he noticed that Jesus himself says

"You heard me say, ‘I am going away and I am coming back to you.’ If you loved me, you would be glad that I am going to the Father, for the Father is greater than I."
John 14:28

Presbyter Arius began to look at the very beginning of everything and concluded that there must have been a time before Jesus Christ existed since he is called Son of God.

It is obvious, is it not, at least according to our human language and logic that if there is a Father and He has a Son, the Father was before the Son.


Wikipedia article summarizes all this nicely:

"Arius taught that God the Father and the Son did not exist together eternally.
He taught that the pre-incarnate Jesus was a divine being created by (and therefore inferior to) God the Father at some point, before which the Son did not exist.
In English-language works, it is sometimes said that Arians believe that Jesus is or was a "creature", in the sense of "created being". Arius and his followers appealed to Bible verses such as where Jesus says that the father is "greater than I" (John 14:28), and says "The Lord created me at the beginning of his work" (Proverbs 8:22) although this verse is now generally held by trinitarians to refer to some concept of "wisdom" rather than to the Son of God.
Of all the various disagreements within the Christian Church, the Arian controversy has held the greatest force and power of theological and political conflict, with the possible exception of the Protestant Reformation. The conflict between Arianism and Trinitarian beliefs was the first major doctrinal confrontation in the Church after the legalization of Christianity by the Roman Emperors Constantine I and Licinius."
Quoted from wikipedia


Tares among the wheat (darnel)
The teaching of Arius was not only a powerful catalyst in the development of Church teaching about Trinity that challenged the greatest minds in early Byzantine period from St Athanasius and St Augustine to the Cappadocian Fathers.

It was also tares among the wheat that spread among the wheat in the fields of Christ. The most significant believers who followed Arian teaching were the fearsome Goths approaching the borders of the Roman empire and eventually breaking in with devastating consequences to the classical world in events that changed the history of the world.

The growth of the Kingdom of Christ in Europe at these turbulent times was strongly influenced by Arian Christology from the regions of modern Yugoslavia all the way along the northern borders of Roman empire and to Spain.

A key person in this sowing of the darnel was Wulfila who brought many pagan Gothic tribes to Christ the Created One.


Arianism today
Because the teaching of Arius makes sense - of course Father is greater than Jesus, God is eternal, invisible, One - probably quite many baptised Christians today have similar ideas about the relationship between God and Christ at the back of their heads even when confessing the Nicene Creed by their mouths.

Trinity is a tough doctrine because it is so paradoxical and does not fit into the mighty power of our brains!

Go ask St Augustine if you do not agree with me on this!

One God, One Empire, One Emperor

Dough and yest

"The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till it was all leavened."
Jesus Mt 13:33

The leaven of Kingdom of Heaven was spreading around the Mediterranean as faith in Jesus spread rapidly from heart to heart. People were taught to keep what Jesus had told them to keep and they came to be baptized despite of the cruel and bloody persecution of the Church.

We can look at the policy of persecution - and its reversal by Constantine the Great and Licinius - as a political act. The Empire was made up of so many conquered nations, cultures and religions, that it needed something to bond it together. The cult of the Caesar was such a binding element that was acceptable to all and sacrificing for the good of the Emperor by the Eagle an act of civil obedience. By refusing to sacrifice Christians were a danger to the inner unity of the Empire as religion had an important social and political function in ancient Rome.


It's No Sacrifice

 The Roman Eagle standard used in the movie Gladiator

(PropStore)

Why did the not go along and sacrifice by the eagle standard and altar to the good of the Emperor? (Some actually did). Had they not refused Christianity would have been just another cult among the many, competing with Mithra or Isis. With no salt, no difference and no role in shaping world history. By sticking to One God and refusing pagan worship of the Emperor, even by the extreme price paid by Saint Perpetua and Felicia and so many others, Christians became a meaningful entity. Very meaningful.


Decisive victory for Christ in Milan!

 Constantine the Great (ref)

Constantine knew first hand the futility of Diocletian's persecution of Christians and he had seen its horrible consequences. He deeply loved his Christian mother Helena and respected her religion. But when he and Licinius reversed the religious policies of the State by the Edict of Milan in February 313 and made faith in Christ an allowed religion (religio licita) this they did not change the basic configuration. Religion was still seen as a political entity that was needed to keep keep internally together the huge Empire. The Edict just changed the key religion and in addition to Jupiter and Sol invictus also faith in Jesus Christ, Rex Regum, was now officially allowed.

The victory for Jesus at Milan was enormous because He is a living God, not a false god like Dio or Sol. So Jesus was now able to mobilize new and very powerful forces to the battle in His request to conquer the entire world. Suddenly such a goal did not look such a crazy and impossible dream as it must once have been in the eyes of His first disciples in Galilee.


Unity of faith is unity of Empire
From the background of fundamental political significance given to the new religion in Roman ideology we can easily understand the horror at which Constantine looked at the great diversity and myriads of quarrels in the Christian communities coming out from the closet. Instead of confessing a single faith in God and living in peace there were bitter, often bloody, quarrels about almost everything in the faith. Who is God, who is Christ, what is Church, who is the boss of the Christians...? 

Constantine decided to step in and fix the problem of diversity in faith for once and for all. For this purpose the Emperor invited all 1800 Christian bishops to join a common (Ecumenical) council to be held in the city of Nicaea (modern Iznik in Turkey). They were to work out consensus about their doctrinal, hierarchical and practical differences and unite as a single Church under the benevolent rule of a single Emperor for the good of a single Empire.

About 318 of the invited bishops arrived to Nicaea some of them badly disfigured by torture in Roman jails, and sat down to work out the theological borders of the Kingdom of God.

The Bishops discussed
The Arian question regarding the relationship between God the Father and Jesus the Son
The date of celebration of the Paschal/Easter observation and Jewish calendar
The Meletian schism
The validity of baptism by heretics
The status of the lapsed in the persecution under Licinius
(For more details see the excellent wikipedia article on First Council of Nicaea) 

The result of the discussions was compressed in what is known today as the Nicene Creed. It is simply the foundation of  Christian theology and those who do not accept it are considered to be outside the Kingdom of God.

Nicene Creed has remained unchanged after the modifications and additions of the Ecumenical Council of Constantinopol in 381 A.D.

The later probably fifth century "Spanish addition" to the creed (et filioque) has only been accepted by the Western church and still today remains an open wound in the body of Christ.


Original Creed of Nicaea Anno Domino 325
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 [the only-begotten; that is, of the essence of the Father, God of God], Light of Light, very God of very God, begotten, not made, being of one substance with the Father;

By whom all things were made [both in heaven and on earth];

Who for us men, and for our salvation, came down and was incarnate and was made man;

He suffered, and the third day he rose again, ascended into heaven;
From thence he shall come to judge the quick and the dead.

And in the Holy Ghost.