The 
Council of Chalcedon took place in 
451 A.D.  It is the fourth of the first seven 
Ecumenical Councils in 
Christianity, and is therefore recognized as infallible in its dogmatic definitions by the Roman Catholic and Eastern Orthodox churches.  It set forth the 
Chalcedonian Creed, which describes the full humanity and full divinity of 
Jesus Christ, the second person of the 
Holy Trinity.  Ecumenical councils after the seventh are recognized as infallible only by Roman Catholics.
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