Against Ecumenism http://www.orthodox.net/articles/against-ecumenism.html
This verse clearly and directly states that Christians must stay together, speaking, thinking and believing the same things. Orthodoxy, which has held the Christian faithful together in one divine body for two millennia, is the perfect fulfillment of these instructions. In the Orthodox Church, the faithful conform their minds and will to the sacred teachings of the faith, and this brings perfect spiritual unity.
If we are not of one mind, we are in direct disobedience to the Gospel, to the Church, and to Christ. To be of one mind, we must follow the teachings of and conform ourselves to the ancient Christian Church, the true Church of Christ, the Orthodox Church.
O Holy Lord Jesus Christ, help us to remain steadfast in the holy teachings of Thy church and disallow false ways of believing, thinking and living to corrupt and scatter Thy flock! Grant that we may preserve unsullied the pearl of great price given unto us, keeping it inviolate for all generations to come, through the prayers of Thy most pure Mother and of all the saints. Amen.