7. Affirm the Trinity
In invoking the name of God the Father, the Son, and the Holy Spirit, we are affirming our belief in a triune God. This is also reinforced by using three fingers to make the sign, according to Pope Innocent III.
8. Focus our prayer on God
One of the temptations in prayer is to address it to God as we conceive of Him—the man upstairs, our buddy, a sort of cosmic genie, etc. When this happens, our prayer becomes more about us than an encounter with the living God. The Sign of the Cross immediately focuses us on the true God, according to Ghezzi: “When we invoke the Trinity, we fix our attention on the God who made us, not on the God we have made. We fling our images aside and address our prayers to God as he has revealed himself to be: Father, Son, and Holy Spirit.”
9. Affirm the procession of Son and Spirit
In first lifting our hand to our forehead, we recall that the Father is the first person the Trinity. In lowering our hand we “express that the Son proceeds from the Father.” And, in ending with the Holy Spirit, we signify that the Spirit proceeds from both the Father and the Son, according to Francis de Sales.