LORD is king, the peoples tremble;
God is enthroned on the cherubim, the earth quakes. ...
Let them praise your great and awesome name: Holy is God! ...
Exalt the LORD, our God; bow down before his footstool; holy is God!
click image to hear "Holy God" by Katerina
God is Holy . The Hebrew word means separate or other but a fuller appreciation of its meaning may be had by reading Exodus 3. As Moses was approaching the "Burning Bush" he was told to remove his sandals because he was standing on holy ground. The ground is made holy by the mysterious presence of someone other-worldly. Moses hid his face because he was afraid to look upon the face of God, that is, "looking" at a presence full of power, majesty and glory which human nature could not stand. God revealed his name to Moses -- "I AM" meaning he who was, is and will be forever. Boethius defines the Eternal as the "whole, perfect and simultaneous possession of endless life". So God is Holy not only because He is separate from his creatures but primarily because He is fullness of Being, Life, Power, Wisdom, Majesty and Glory.
Man was created in the image of God, with a wholeness or integrity of being resembling God, but his revolt against the living God brought about a certain disorder in his being subjecting him to estrangement from God and his fellow men, proness to the disorder of sin leading him toward suffering and death. So God the Father had compassion on us and sent his only Son to sanctify us or restore us to holiness.
Christ gave authority to the apostles to sanctify when he told them to baptize, heal the sick, forgive sin, change bread and wine into his body and blood, etc. but the power to do this was bestowed upon the Church with his death/resurrection which released the power of the Spirit upon his followers. The Church is the Mystical Body of Christ, that is, that social order which believes that Christ is the Son of God, hopes in his promises and loves with supernatural love. This is where Christ is present and active amidst humanity in a visible and tangible way.
The Church sanctifies by means of Word and sacraments (Sacred Signs), words and actions which bring about what is signified. They are not mere symbols but words/actions which bring about what is signified "ex opere operato" "by the very fact of the action's being performed". They are effective regardless of the minister's state of soul.
"The purpose of the sacraments is to sanctify men, to build up the Body of Christ and, finally, to give worship to God. Because they are signs they also instruct. They not only presuppose faith, but by words and objects they also nourish, strengthen, and express it. That is why they are called 'sacraments of faith.'" (Catechism of Catholic Church, # 1123)
Christ has given the Church authority and power to sanctify mankind and the Church is necessary for the salvation of mankind, but He is not limited by the Sacraments. The Church teaches ''Since Christ died for all, and since all men are in fact called to one and the same destiny, which is divine, we must hold that the Holy Spirit offers to all the possibility of being made partakers, in a way known to God, of the Paschal mystery. Every man who is ignorant of the Gospel of Christ and of his Church, but seeks the truth and does the will of God in accordance with his understanding of it, can be saved. It may be supposed that such persons would have desired Baptism explicitly if they had known its necessity." (Ibid., #1260)