Saint Ireneus
2nd Bishop of Lyon, Theologian of Unity
He held passionately the truth that there is only one faith, one true Church founded on Jesus and the teaching of the Apostles
Unity of the Faith
"As I have already observed, the Church, having received this preaching, and this faith, although scattered throughout the whole world, yet, as if occupying but one house, carefully preserves it. She also believes these points of doctrine just as if she had but one soul, and one and the same heart, and she proclaims them, and teaches them, and hands them down, with perfect harmony, as if she possessed only one mouth. For, although the languages of the world are dissimilar, yet the import of the tradition is one and the same. ..."
Unity of the Church
"... For the Churches which have been planted in Germany do not believe or hand down anything different, nor do those in Spain, nor those in Gaul, nor those in the East, nor those in Egypt, nor those in Libya, nor those which have been established in the central regions of the world. But as the sun, that creature of God, is one and the same throughout the whole world, so also the preaching of the truth shineth everywhere, and enlightens all men that are willing to come to a knowledge of the truth. (Ireneus: Against Heresies vol 1, 10,2)
Unity of God - Unity of Christ - Unity of Revelation
Unity of Man - Unity in Man
"For where the Church is, there is the Spirit of God; and where the Spirit of God is, there is the Church, and every kind of grace; but the Spirit is truth." (Ireneus: Against Heresies vol 3, 24,1)