Why the priest kisses the altar01 Jul 2017, by Doctrines in
I once mentioned to a convert to Catholicism the need to understand the Church properly to enjoy our style of worship. The Catholic faith is enshrined in many cases, and our liturgy is full of signs and symbols that make some none Catholics criticize Catholicism in ignorance. One of the beautiful signs but not understood by a few Catholics and many none Catholics is the kissing of the altar at the beginning and end of Mass by the priest.
At the beginning of the Mass, the priest kisses the altar, and many Catholics have become so familiar with this gesture that they no longer attach meaning to it. But it is a sign, a gesture that expresses something very significant about our Catholic Tradition.
To begin with, the altar is a table of sacrifice on which the body and blood of Jesus Christ is offered to the Father. At Mass, Jesus is the priest, the victim of the sacrifice and the altar. How he is the priest and the victim of the sacrifice, I presume you know (in case you don’t, he acts in the priest and he is the Lamb of the sacrifice), but how Jesus is the altar may make you wonder.
Traditionally the altar is made of stone, symbolically representing Christ the cornerstone; we express our faith in Christ who was rejected but became the keystone. The altar is also traditionally not moveable, symbolically expressing our faith in Christ, the unmoved mover of all things. So, the priest kisses the altar as a sign of respect and love for Christ as well as greetings. He also kisses the altar to venerate the relic of the saints buried under the altar.
The Church has the tradition of burying the relic of saints under the altar; the history behind this tradition is interesting. During the first centuries of church history, Masses were often celebrated in the underground catacombs on stone slabs covering the tomb of a martyr. This was done in order to reverence the martyr and their heroic and ultimate sacrifice for the Lord. This also was done out of necessity: Being a Christian was illegal throughout the Roman Empire (thus the existence of martyrs) and the Mass had to be celebrated in secret. But as Christianity became legal and Churches were built, the relic of saints was put under the altar rather than their tombs.
Therefore, kissing the altar is a sign of greeting, respect, and love for Christ, the priest, the altar, and the Lamb of the sacrifice. And it is also to venerate the relic of the saints.