Why Do Catholics Make the Sign of the Cross?

Catholics make the sign of the cross because it is a brief profession of the Christian faith, which we received from the Apostles. 'Through the Sign of the Cross we place ourselves under the protection of the Triune God.' (CCC 2157)

As often as we make the sign of the cross in the name of the Father, and of the Son, and of the Holy Spirit, we are saying that we believe in God, a Trinity of three persons, and the Redemption of the Cross.