Before celebrating every Mass the priest (and deacon) approach the altar and kiss it. What is the significance behind this ancient custom?
Kissing holy and sacred objects has been part of various world religions for thousands of years. As Christians developed the liturgy they adapted customs from their own culture and gave them new significance.
The altar receives its importance in connection with the Holy Sacrifice of the Mass that is celebrated upon it. It has been set apart for this purpose and the bishop consecrates it when it is installed in a new church. In a ceremony resembling Baptism the bishop uses holy oils to bless the altar and vests it with a white garment.
Symbolically the altar is often said to represent Jesus Christ, the “cornerstone” of the Church (cf. Ephesians 2:20). Throughout the history of the liturgy the priest would sometimes kiss the altar before blessing the people, symbolizing how the blessing came from God, not the priest. Relics of saints were inserted into the altar and when the priest kissed the altar, he would be kissing the relics as well.
Kissing the altar recognizes its privileged role and relation to the divine sacrifice of Jesus Christ.
Philip Kosloski, This is why the priest kisses the altar at Mass.
Excerpted from Aleteia.com, July 26, 2017. With permission.