The author of the article starts from the classical become question, „what is the truth?” and intents to discover if there is a specific Christian concept of truth. The fundament of the study is constituted by the writings of saint apostle and evangelist John, the one that imprinted with his vision the Christian conception of truth. Thus, in the first part of the article, the author shows the originality of saint John’s concept of truth, in comparison with the Hebrew tradition, on one side, and the Greek and gnostic tradition, on the other side. In the second part, the author analyses the various texts of John that refer to the truth, structuring them in three categories: Christ and the truth, the Holy Spirit and the truth, the Christian and the truth. From this analysis, results that the truth in its Christian dimension, in comparison with the profane conceptions, is more complete and synthetic. It reunites in itself the various aspects that we see developing, isolated, in other systems. The unifying element of the Christian synthesis is the idea of revelation. The term of truth, in the Christian sense, doesn’t indicate God in itself, as the classical metaphysics did, but God’s revelation. In the Christian language, „the truth of God” isn’t the divine substance, but the revelation that comes from God, the revelation of his mysterious redeeming plan that found its definitive fulfilment in Jesus Christ. The Christian conception of the truth, is totaling. It is, in the same time, the memory of the past, an opening towards God’s mystery, the eschatological hope and the existential assimilation. These four dimensions of the Christian truth can be lived only in faith, hope and in a life of love.