The Holy Spirit (Lat. spiritus sanctus) is the third person in the Holy
Trinity and together with the Father and the Son forms the Threefold
God. This creed was announced at the Council of Nicaea in 325 AD which
was convened by Emperor Constantine. The Holy Spirit is thus not seen as
an impersonal force or something vague, but as a person just as God the
Father and Son are.
It is an important function of the Holy Spirit to spread the glad tidings of Jesus, he is the teacher of all Christians. All humans who trust in Jesus are filled by the grace of the Holy Spirit. It lives in them and forms the innermost of man with love, joy, peace, patience, friendliness, goodness, loyalty, docility and self-control. If one trusts in God, then one lives “in the Spirit”, all else comes on its own. The Holy Spirit also has the ability to bring one back to the right path. And often it lets man know that a life without God has its consequences.
The Bible mentions the Holy Spirit several times, for instance when Mary, Mother of God conceives through the Holy Spirit, when it comes down upon Jesus when he is baptised, when Jesus is holding his last speech to the Apostles and in many other places in the Bible. The seven gifts of the Holy Spirit (which belong to the formulae of the Catholic Church) are: the Gift of Wisdom, of Understanding, of Counsel, of Strength, of Knowledge, of Godliness and of Holy Fear. Christians receive the Holy Spirit through their confirmation so as to strengthen the spiritual ties to God and to testify for the Christian Faith in word and deed. The Catholic Church holds this sacrament to be the completion of baptism. The confirmation candidates usually receive from the bishop between their 13th and 17th year.
On the fiftieth day after Easter, the Catholic Church celebrates Pentecost (Greek pentekoste = the 50th day). This is another very important feast day which commemorates the sending of the Holy Spirit to the apostles. Christians traditionally regard this day is as the founding date of the Church. It is a legal holiday in many countries around the world. It is also the ceremonial end of the Easter period.