Introduction to the Ceremony
Symbolically, the word "church" speaks not only of the building that houses the gathering of Christ’s Faithful, but also the gathering of the Faithful itself.
The liturgy of the Dedication in which we shall take part highlights this symbolism. During its successive stages, it will constantly refer to, and link, the visible building to the "City of the Living." The link will often be based on the evocation of Jerusalem, which is an archetype of the Church, and in which the first temple of God had been raised. This is why the psalms shall be sung all throughout the rites of purification and of "possession," as well as through the solemn transfer and burial of the martyrs’ relics, the consecration of the walls and of the altar with Sacred Chrism, and, at last, the celebration of Holy Mass. These psalms reflect ancient Israel’s love for the Holy City and the Temple, and at the same time raise our sight to the New Jerusalem, whose temple is the Lamb Himself (Apoc. 21,22)
Therefore the ceremony of the Dedication of a church is four-fold:
Firstly, the Lustration, or Washing of the Church (performed both outside and in, this ceremony purifies the church and prepares it for the consecration. The water, called "Gregorian," has been specially blessed for this occasion.)
Secondly, the Translocation and Deposition of the relics.
Thirdly, the Consecration (consecration of the Church by the unction on the twelve crosses, and the consecration of the altars.)
Finally, the Pontifical Mass in the newly consecrated Church.
It is good to bear in mind that the church symbolizes the Incarnate Word, the Mystical Body (presence of the relics) and that the ceremony renews the spiritual birth of every Christian life with baptism (Lustration), Confirmation (Chrismal Unction), and the Eucharist (Mass).
Fonte: ICRSS