5. The mystery of the Holy Trinity
The most important secret of divine faith that Jesus Christ revealed is the mystery of the Holy Trinity. Jesus told about his Father (God) and the Holy Spirit (God); and said that he and his father are one (John 10:30), because he is the Son of God. The Father, the Son and the Holy Spirit are one God and not three because they have the same divine nature, although there are three really distinct entities.
The revelation of his private life is that God is one in essence and triune (three) in entities. It is the greatest and deepest of all mysteries. It is also the fundamental mystery of our faith and our Christian life. We should try to know and live it! the Creed or Symbol is the explanation of the Trinitarian mystery: what God is and what he has done for his creatures with the creation, the redemption and the sanctification.