The Catechism in Questions & Answers

617. Is God present in the divine service?

Yes. At the beginning of the divine service, God is invoked with the words: “In the name of God, the Father, the Son, and the Holy Spirit”. This invocation of God is called the “Trinitarian opening formula”. This makes it clear to those attending the divine service that God is present, just as the Son of God promised (cf. Matthew 18: 20).