However, because of the Ottoman Turkish threat a further attempt was made for a union.  It was believed that all could be forgotten if the west defended the east against the Turks.  

A conference was set up in Florence in 1438 and lasted two years.  A union was almost assured accept for the resistance of St. Mark of Ephesus.  St. Mark felt that union could only occur if there was a return to the faith set up by the Holy fathers of the church.  He deemed it more appropriate to live as slaves to the Turks then dishonor God by abandoning the Orthodox religion.  Out of the 17 bishops that attended the conference he was the only one who voted against the union.  He was so well respected that when the Pope heard of his rejection he replied "All that we have done is nothing."

As a result of St Marks resistance to a union that would not preserve the Orthodox religion he was declared a saint, and is hailed as the atlas of Orthodoxy being celebrated on the 19th of January.

It could be said that St. Mark preserved the Orthodox religion through his rejection of a union that did not return to the roots of Christianity. 

As a result of the resistance of the population to a union, and the occupation of the east by the Ottoman Turks union would no longer be discussed for many centuries.

Currently there is an Ecumenical  movement with the aim of uniting the Christian churches.  Many bishops of the Orthodox church do not wish to see a union that results in the end of Orthodoxy, among them is the  Patriarch of Jerusalem.  They wish to see a union, but resist union for the same reasons as St. Mark.