The current theology of the trinity wasn't solidified until the 4th century, yet we accept that. Why can't we accept a doctrine of self-defense and just war?

I want to begin with a lengthy quote from Roland Allen's book, "The Spontaneous Expansion of the Church." 

​THE GREAT HERESIES IN THE EARLY CHURCH AROSE NOT FROM THE RAPID EXPANSION RESULTING FROM THE WORK OF THESE UNKNOWN TEACHERS; BUT IN THOSE CHURCHES WHICH WERE LONGEST ESTABLISHED, AND WHERE THE CHRISTIANS WERE NOT SO BUSILY ENGAGED IN CONVERTING THE HEATHEN ROUND THEM. THE CHURCH OF THAT DAY WAS APPARENTLY QUITE FEARLESS OF ANY DANGER THAT THE INFLUX OF LARGE NUMBERS OF WHAT WE SHOULD CALL ILLITERATE CONVERTS MIGHT LOWER THE STANDARD OF CHURCH DOCTRINE. SHE HELD THE TRADITION HANDED DOWN BY THE APOSTLES, AND EXPECTED THE NEW CONVERTS TO GROW UP INTO IT, TO MAINTAIN IT AND TO PROPAGATE IT. AND SO IN FACT THEY DID. THE DANGER TO THE DOCTRINE LAY NOT IN THESE ILLITERATE CONVERTS ON THE OUTSKIRTS; BUT AT HOME, IN PLACES LIKE EPHESUS AND ALEXANDRIA, AMONGST THE MORE HIGHLY EDUCATED AND PHILOSOPHICALLY MINDED CHRISTIANS. IT WAS AGAINST THEM THAT SHE HAD TO MAINTAIN THE DOCTRINE.
 
NOW ALL THIS SUGGESTS QUITE A DIFFERENT ATMOSPHERE FROM THAT WITH WHICH WE ARE FAMILIAR. THE CHURCH OF THOSE AGES WAS AFRAID OF THE HUMAN SPECULATION OF LEARNED MEN: WE ARE AFRAID OF THE IGNORANCE OF ILLITERATE MEN. THE CHURCH THEN MAINTAINED THE DOCTRINE AGAINST MEN WHO WERE CONSCIOUSLY INNOVATING: WE MAINTAIN THE DOCTRINE AGAINST MEN WHO MAY UNCONSCIOUSLY MISREPRESENT THE TRUTH THAT THEY HAVE LEARNT. THE CHURCH THEN MAINTAINED THE DOCTRINE BY HER FAITH IN IT: WE MAINTAIN OUR DOCTRINE BY DISTRUSTING OUR CONVERTS' CAPACITY TO RECEIVE IT. THE CHURCH THEN MAINTAINED HER DOCTRINE BY THINKING IT SO CLEAR THAT ANY ONE COULD UNDERSTAND IT: WE MAINTAIN OUR DOCTRINE BY TREATING IT AS SO COMPLICATED THAT ONLY THEOLOGIANS CAN UNDERSTAND IT. CONSEQUENTLY, THE CHURCH THEN WAS QUITE PREPARED THAT ANY MAN WHO BELIEVED IN CHRIST SHOULD TEACH OTHERS WHAT HE KNEW OF HIM: WE ARE ONLY PREPARED TO ALLOW MEN WHOM WE HAVE SPECIALLY TRAINED TO TEACH IT. WHEN OTHERS WHOM WE HAVE NOT SPECIALLY TRAINED OF THEIR OWN SPONTANEOUS MOTION DO TEACH OTHERS WE HASTEN TO SEND A TRAINED TEACHER TO TAKE THEIR PLACE. THAT IS, OF COURSE, EXACTLY WHAT THE EARLY CHURCH DID NOT DO, YET IT MAINTAINED ITS STANDARD OF DOCTRINE. 
 
AND HERE I WOULD RECALL THE FACT THAT IN ALL THOSE SPORADIC CASES OF SPONTANEOUS TEACHING WITH WHICH WE ARE FAMILIAR IN OUR OWN DAY WE NEVER HEAR OF ANY DELIBERATE CORRUPTION OF CHRISTIAN DOCTRINE. WHEN OUR MISSIONARIES DISCOVER THESE CASES, THEY NEARLY ALWAYS FIND THAT THE TEACHING GIVEN IS, SO FAR AS IT GOES, TRUE, AND IS VERY OFTEN SURPRISINGLY TRUE AND DEEP. THESE CONVERTS SEEM TO HAVE LEARNED BY THEMSELVES MUCH THAT WE THINK CAN ONLY BE TAUGHT BY US. AND WHAT THEY HAVE LEARNED IS VERY FUNDAMENTAL. AND THEY SEEM ALSO INVARIABLY TO SHOW A GREAT READINESS TO LEARN MORE. NOW THAT IS NOT THE SPIRIT WHICH BREEDS HERESY.THE SPIRIT WHICH BREEDS HERESY IS A SPIRIT OF PRIDE WHICH IS PUFFED UP WITH AN UNDUE SENSE OF ITS OWN KNOWLEDGE AND IS UNWILLING TO BE TAUGHT.
 
THE REASON WHY THE SPONTANEOUS ZEAL OF NEW CONVERTS DOES NOT BREED THAT SPIRIT IS NOT HARD TO FIND. SUCH CONVERTS ARE ALMOST INVARIABLY MEN WHO HAVE HAD SOME REAL RELIGIOUS EXPERIENCE. THEY HAVE HEARD SOMETHING OF CHRIST; THEY HAVE RECEIVED SOME TEACHING ABOUT HIM; THEY HAVE GENERALLY LEARNED TO REPEAT THE CREED AND TO READ THE BIBLE; THEY HAVE CALLED UPON CHRIST AND BEEN HEARD; AND THIS HAS WROUGHT A CHANGE IN THEIR WHOLE OUTLOOK UPON LIFE, SUCH A CHANGE THAT THEY ARE EAGER THAT OTHERS SHOULD SHARE THEIR EXPERIENCE. HENCE THEY BEGIN TO TEACH OTHERS, AND TO SHARE THEIR EXPERIENCE WITH OTHERS. NOW ALL RELIGIOUS EXPERIENCE DEMANDS DOCTRINE FOR ITS PROPER STATEMENT AND EXPLANATION. IF THEN THESE MEN ARE NOT WELL INSTRUCTED IN THE CHRISTIAN DOCTRINE, WHEN THEY ATTEMPT TO SHARE THEIR EXPERIENCE WITH OTHERS THEY FEEL THAT THERE IS MUCH IN IT WHICH THEY CANNOT UNDERSTAND. CONSEQUENTLY INSTRUCTION IN CHRISTIAN DOCTRINE COMES TO THEM WITH AN ENLIGHTENMENT AND A POWER WHICH IS A JOY, AND THEREFORE THEY GLADLY RECEIVE IT, BECAUSE IT SUPPLIES A FELT NEED OF THEIR SPIRITUAL EXPERIENCE. IN SUCH AN ATMOSPHERE CHRISTIAN DOCTRINE IS IN LITTLE DANGER, FOR THOUGH FALSE OR INADEQUATE TEACHING, IF THEY RECEIVED SUCH, MIGHT PREVAIL FOR A TIME, YET THE TRUE TEACHING WHEN IT COMES MUST INEVITABLY DRIVE OUT THE FALSE. FOR THE EXPERIENCE IS A TRUE EXPERIENCE, AND A TRUE EXPERIENCE DEMANDS A TRUE DOCTRINE. IT IS AS THE COMPLEMENT OF EXPERIENCE THAT CHRISTIAN DOCTRINE FIRST TOOK SHAPE. IT IS NOTORIOUS THAT THE CHRISTIAN DOCTRINE OF THE TRINITY, FOR INSTANCE, WAS FORMULATED THROUGH THE ATTEMPTS OF THE DISCIPLES OF CHRIST TO EXPLAIN THEIR EXPERIENCE. CHRIST APPEARED, AND THE APOSTLES EXPERIENCED HIS POWER: THE HOLY GHOST DESCENDED, AND THE APOSTLES AND THEIR IMMEDIATE FOLLOWERS KNEW HIS INDWELLING; THE CHRISTIAN DOCTRINE OF THE TRINITY AROSE OUT OF ATTEMPTS TO EXPRESS THAT EXPERIENCE.
 
AS THE COMPLEMENT OF EXPERIENCE, DOCTRINE RENEWS ITS YOUTH FROM AGE TO AGE; BUT DIVORCED FROM EXPERIENCE IT IS NOTHING MORE THAN THE STATEMENT OF AN INTELLECTUAL THEORY, AND TO REST IN SOMETHING WHICH AN INTELLECTUAL PROCESS HAS CREATED IS TO REST IN THAT WHICH AN INTELLECTUAL PROCESS CAN DESTROY… 

The last paragraph summarizes one of Allen's main points, which is that doctrine must be a description of our experience with God. Our God is a living God and our religion is centered around relationship. We are not stalkers of God, but friends, servants, and communers of God. The doctrine of the trinity was formed from experience. The Apostles encountered Christ and he was truly human. They encountered Christ and he was truly God. No doctrine could be formed which did not adhere to these two experienced truths. The doctrine took so long to solidify because the true experience of God couldn't let humanity get away with rationalizing how we think God should work. The experience of God held theology ransom until it aligned.

First, I would argue that the theology of the trinity was debated pretty thoroughly for several hundred years. To my knowledge you don't see the same sort of thing occurring with non-violence. The church was fairly univocal for the first few hundred years. Sure, the topic wasn't covered nearly to the same extent, but you just don't have the same sort of back and forth you have with the discussion of the trinity.

Second, the lack of debate seems to have a pretty clear source - there was no room for a competing view. The early church struggled to explain the trinity because they had two seemingly competing ideas. They thought they had a paradox, when in reality they had an antinomy. How can Christ be God and human? To see the same sort of debate about violence vs. non-violence, there would have to be two competing foundations - a seemingly non-violent Jesus and a seemingly violent Jesus. But the early church seemed to only recognize a non-violent Christ and non-violent commands, as he reserved all judgment and violence for his coming.

Third, it wasn't until the empire and the church merged and philosophizing began that a non-violent approach was explained away. Allen points out that it is rationalizing and philosophizing that tend to create doctrinal problems - as you move away from explaining experience. The experience of Jesus and his means was clear to the Apostles, and they made it clear to their disciples. The early church didn't have a problem with non-violence because as an experience of Christ, it made sense. It wasn't until they began trying to figure out how to fit God into the empire that things began to change, as they moved away from describing their experience with Christ. 

The power of the pacifistic position comes in the fact that it is not only the most natural reading of Christ's and the Apostles's teachings, but it is also the common practice of the early church. You have some teachings, like the trinity, which aren't explicitly taught in the Bible, and are only solidified a few hundred years after the establishment of the church. You have other practices, like the sharing of property, which are early traditions in the church, but not explicit teachings. Pacifism doesn't fit either of these categories. Pacifism, unlike the trinity, is less a deduction and more of a natural reading. Along with being the most natural reading of the text, pacifism is also the common practice of the early church. When you find something that is both early tradition (as opposed to developed tradition) and the most natural reading of explicit teaching from Christ and the apostles, you have a very hard teaching to overturn.