The Holy Mysteries of the Church are otherwise known (in the Latin and Protestant Churches) as the "Sacraments."
The Holy Mysteries are one of the three things that unite us to God. The other two ways which unite us to God are prayer and fasting.
Our Lord, God and Savior, Jesus Christ gave us, through His Holy Catholic Church, seven Holy Mysteries. These seven Holy Mysteries are:
Baptism
Chrismation
Holy Eucharist
Repentance
Holy Unction
Holy Ordination
Holy Crowning
BAPTISM: is the sacrament of regeneration by water in the word. The word Baptism is derived from the Greek word, bapto, or baptizo, to wash or to immerse. It signifies, therefore, that washing is of the essential idea of the sacrament.
CHRISMATION: completes the sacrament of Baptism. If Baptism is the sacrament of regeneration and re-birth to a new and supernatural life, Confirmation is the sacrament of maturity and coming of age.
HOLY EUCHARIST: celebrates our life together as a Community, the presence of Christ in our midst, the Word that is proclaimed and explained, many dimensions of the paschal mystery of death and rebirth. We celebrate our unity with Christ in communion and service.
REPENTANCE: celebrates and reminds us of God's mercy and helps us to experience divine forgiveness, to forgive ourselves, and to become reconciled with others.
HOLY UNCTION: As confirmation by conferring the Holy Spirit completes the sacrament of Baptism, so the anointing of the sick is the complement and completion of Reconciliation. It celebrates and reminds us of God's compassion and helps us to experience spiritual and physical strengthening when we are ill.
HOLY ORDINATION: integrates men into the holy orders of Deacons, Priests, and Bishops; empowering them for a lifetime of leadership and service in the Church.
HOLY CROWNING: The sacrament of Matrimony signifies the union of Christ and the Church. It gives spouses the grace to love each other as Christ loved His Church; the grace of the sacrament thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life.