The two Fathers knew that the truth about God is based on the texts of the Holy Scriptures. It is developed theologically from the texts of earlier Church Fathers. The truth of God is shielded or in a better way it is immured against the heretical doctrine by the decisions and the conditions of local and mainly the Ecumenical Councils. So, it is clearly taught that God is one and the same time Trinity. They entrenched the theology of the Church against heretics and pagans of various traps, in their time and the later years. They pointed out, moreover, that the Triune God is living, life-giving and personal and He unveiled to the world through the midst of his second. The man, on the other hand, is not susceptible of the approximation of the mystery of the Trinity midst thoughts and reasoning, because of his finite mind. Someone can obtain the knowledge of God through the incarnation of our Lord Jesus Christ and by the grace of the Holy Spirit. They follow Athanasius', Cappadocians’ theology and the teaching of the first Ecumenical Council, which identifies the termsHypostasis and ousia. Cyril was influenced by Isidore and emphasizes that in the Holy Trinity there is no place nor the time, nor the class and neither order among the persons of the Triune God. Both Fathers considered that the vocabulary of human language is finite so it cannot express the Infinite Divine. So the words are used in an abusive importance.