Why do we bless ourselves with Holy Water when we enter the church? (OR, in COVID Times: Why does Fr. Francis sprinkle us with Holy Water before Mass?)

Besides remembering Christ’s passion and professing their faith in the Holy Trinity, Catholics bless themselves with holy water primarily as a reminder of our Baptism.
The Catechism of the Catholic Church explains: “The symbolism of water signifies the Holy Spirit’s action in Baptism, since after the invocation of the Holy Spirit it becomes the efficacious sacramental sign of new birth: just as the gestation of our first birth took place in water, so the water of Baptism truly signifies that our birth into the divine life is given to us in the Holy Spirit. As ‘by one Spirit we were all baptized,’ so we are also ‘made to drink of one Spirit.’ Thus the Spirit is also personally the living water welling up from Christ crucified as its source and welling up in us to eternal life” (CCC 694).
Leaving the secular and entering the sacred
In addition to being a reminder of the rebirth experienced at Baptism, holy water fonts also provide a practical function that helps us transition from the secular world into the House of God.
The holy water fonts were originally much bigger and were mainly used to cleanse a person’s dirty body before walking into the sacred space. Even Jesus washed the feet of his disciples before celebrating the first Eucharist. While not currently used in that same way, holy water fonts still provide a reminder that before we can enter the “Wedding Feast of the Lamb,” we must wash ourselves and put on the “wedding garment” to be admitted to the table.
In the end, while it is sometimes easy to get into the habit of entering a Catholic church and rushing through the ritual of blessing oneself with holy water, the symbolism behind the act is worth pausing a few extra seconds. It is meant to be a reminder of our Baptism and provides an opportunity to leave behind the secular and enter into the sacred.
(Source: Aleteia.org)

Read more in the “Why Do We Do That?” series from Deacon Mike Fritz.