Third Council of Dvin
The Third Council of Dvin was a church council held in 607 (or 609-610) in the city of Dvin (then in Sasanian Armenia).

Overview
This council (or synod) was the culmination of a series of post-Chalcedon debates on the nature(s) of Christ. The schism within the Armenian Church which had erupted as a result of the second Chalcedonian Catholicosate in Armenia (591-610), was mended, and the  conclusions of the Council of Chalcedon of 451 were explicitly condemned.

The Armenian Orthodox Church concluded that both “monophysitism” and the Chalcedonian Definition were to be condemned. Instead the church decided to follow the doctrine of Cyril of Alexandria, who described Christ as being of one incarnate nature, with both divine and human nature being united.

The synod saw the election of an Armenian, , as Catholicos. Abraham condemned the Council of Chalcedon in accordance  with the decision of the Second Council of Dvin.

Split with the Georgian Church
By the end of the council, the Armenians were fully opposed to the Christological definition given by the Chalcedonian Church. The Georgian Orthodox Church decided to join with Constantinople in upholding the Chalcedonian definition of the dual nature of Christ. This Council established the distinct split between the Armenian and Georgian Churches.

Although a rift was established with the Georgian church, the Council led to mending of an internal rift within the Armenian Church itself. 

A Fourth Council of Dvin was held in 648 to discuss possible reunification with the Georgian church, but this idea was rejected.

Other elements
The council also established seven canon laws regarding the orthodoxy of bishops. In particular, the laws dealt with bishops who had deviated from the faith.

See also
First Council of Dvin
Second Council of Dvin
Fourth Council of Dvin

References

Sources
 
 

Armenian Apostolic Church
7th-century church councils
7th century in Armenia
607
History of Dvin
Christianity in the Sasanian Empire
Sasanian Armenia
600s in the Sasanian Empire