While we know that God is holy, we often forget that God wants that holiness to rub off on us.
God wants to invite us into his divine life, making us holy as he is holy.
The Lord's Prayer begins with a petition that reminds us of that simple fact.
The Catechism of the Catholic Church reflects on this spiritual reality in it section on the Our Father:
In the waters of Baptism, we have been "washed . . . sanctified . . . justified in the name of the Lord Jesus Christ and in the Spirit of our God." Our Father calls us to holiness in the whole of our life, and since "he is the source of [our] life in Christ Jesus, who became for us wisdom from God, and . . .sanctification," both his glory and our life depend on the hallowing of his name in us and by us. Such is the urgency of our first petition.
St. Cyprian expands on this teaching of the Church and how we are "hallowed":
By whom is God hallowed, since he is the one who hallows? But since he said, "You shall be holy to me; for I the LORD am holy," we seek and ask that we who were sanctified in Baptism may persevere in what we have begun to be. And we ask this daily, for we need sanctification daily, so that we who fail daily may cleanse away our sins by being sanctified continually. . . . We pray that this sanctification may remain in us.
St. Peter Chrysologus adds to this reflection, highlighting the need for us to let God's holiness enter into our daily actions:
We ask God to hallow his name, which by its own holiness saves and makes holy all creation. . . . It is this name that gives salvation to a lost world. But we ask that this name of God should be hallowed in us through our actions. For God's name is blessed when we live well, but is blasphemed when we live wickedly. As the Apostle says: "The name of God is blasphemed among the Gentiles because of you." We ask then that, just as the name of God is holy, so we may obtain his holiness in our souls.
Holiness is not something that is only reserved to God and his canonized saints. All of us are called to lead a holy life and to allow God's holiness to radiate through us.