Now if the RCC, the EOC and the OOC could unite into one Apostolic Church, then Protestants might be forced to seriously re-think their position.
Not really. The RCC, the EOC, and the OOC abandoned true New Testament Christianity and enthroned "the doctrines of men". "Tradition" was placed on an equal footing with Scripture. Actually a higher position than Scripture, since tradition has governed these churches more than Scripture.
And Mary took a position in these churches far out of proportion to her role as noted in Scripture. God cannot have a mother, but the Greek churches made her
theotokos = Mother of God, contrary to Scripture. "Mother of Jesus" is what Scripture says, not "Mother of God" (who is the triune Godhead).
Luther was a heretic in the eyes of the RCC, but he was a saint in the eyes of God. Why? Because he searched the Scriptures and put His faith in God and in Christ, and preached that
salvation was purely by GRACE through faith in the Person and finished work of Christ. This fundamental doctrine was abandoned by all the "traditional" churches, and re-instated by the Reformers. Luther's major contribution to Christianity was his German translation of the Bible, which closely resembles the KJV (another Reformation Bible).
What the Reformers failed to do was to take Christians all the way back to true New Testament Christianity. Therefore the Reformers persecuted and killed the Anabaptists, who rejected infant baptism, who rejected baptismal regeneration, and who held to believers' baptism by immersion (as taught in the NT). Thus "Protestantism" also failed (not to mention the Calvinism that permeated Protestantism and distorted the true Gospel).
If Christians today want the Truth, they must go strictly by what is written, as Christ went strictly by what it written, and defeated Satan thereby.