Abstract
Recent research has addressed the problem of the orthodoxy of the teaching of the Synod of Ancyra, but has not dealt directly with the theology of similarity, which is not identical to the theology of the image, although it is close to it. The Synod focused on the similarity of the Son in God’s inner Trinitarian life, claiming that the Son is similar to the Father κατ’ οὐσίαν. It also mentioned the Son’s similarity to us. However, it did not take up the subject of the similarity between man and God or between man and man. The article shows the biblical basis of the synodal theology of similarity and its basic propositions. The difficult expression κατ’ οὐσίαν, defining the similarity of the Son to the Father, is the key to the understanding of the synodal theology. It means the similarity of a person to a person and the unity of persons on the level of substance.