Meriweather
Not all those who wander are lost
Add to that the fact that the Esatern and Western branches never could agree which was to be primal -- Rome or Constantinople. That back-and-forth continued until the Great Schism of 1054 -- which has NEVER been reconciled. Only one of the doctrinal and theological differences that, seeminly, will never be reconciled is the filioque clause in the Creed. So, the idea that there has been One Teaching in the One Church is a little disingenuous, and represents a biased perspective.
The filoque clause should be the easiest to resolve. It's basically a matter of semantics, or more accurately, the differences between the Greek word/definition for "proceeds" and the Latin. Both the East and the West agree that the Holy Spirit initiates with the Father. The Greek word clearly states this.
However, when translated into Latin, things get muddied, because when the word for "Proceeds" is used in Latin, there has to be information about the progression, otherwise nothing happens.
A common analogy is to imagine a game of catch and the Father has the ball (Holy Spirit). The Greek word portrays the ball proceeding from the Father. When (in Greek) "and the son" is added, by definition, two people would now be holding/throwing the same ball. This would be dual procession, the one ball proceeding from two hands. This does not hold true in the Latin, in fact, quite the revers.
In Latin the Father has the ball (Holy Spirit) and there it remains ...until it goes somewhere. Where does it go? Through the Son. In Latin, action must be shown to have taken place, whereas in Greek, the action is perceived to be taking place. This is why when the the Roman Catholic Mass is said in Greek it eliminates "and the Son" for the simple reason that in the Greek it changes from a single progression to a dual progression. If Mass is said in Latin, "and the Son" is included to show a procession is truly taking place. Neither Church believes in dual procession. It is the grammar of two different languages that started the problem--and subsequent issues between the East and the West that blew this out of proportion. Grammar issues are easily resolved.