Mass begins with the Introductory Rite of Greeting. The priest makes the Sign of the Cross: “In the Name of the Father, and of the Son, and of the Holy Spirit.” We all respond with a firm “Amen.” Here we enter again, even more formally, into the presence of the Blessed Trinity, and we recognize that the entire Mass is an act of worship to God, Father, Son, and Holy Spirit.
In fact, the Mass is the highest act of worship and prayer. It is the liturgical rite that God has given to us so that He may be worshiped in the way He has commanded. We give ourselves to Him. He gives Himself to us, Body, Blood, Soul, and Divinity. This is His will for us.
We often hear people claiming that they can pray and worship anywhere and that they do not need to go to church to do so. This is false. Yes, we can and should pray and worship anywhere. But God has given us the Mass as His preferred means of worship. And there can be no greater intimacy with God this side of Heaven than in the Mass, for it is only in the Mass that we participate in Jesus' sacrifice made present on the altar in a unbloody manner.
No, we do not re-sacrifice Jesus again and again as some Protestants claim. That is false, too. Jesus' sacrifice now stands outside of time, and therefore, it remains accessible to us through the liturgy that God has given that we might participate in the sacrifice and have it merits applied to ourselves every day if we so choose.
Further, it is only in the Mass (and because of the Mass) that we receive Jesus in the way He most desires to come to us. At the Last Supper, Jesus first gave Himself to His disciples, Body, Blood, Soul, and Divinity. He continues to give Himself to us in that same intensity every time we receive Him in the Eucharist. It is only in the Mass that Jesus becomes really and truly present in the Eucharist. The bread and wine are truly His Body and Blood in substance. We will not experience the same intimacy with our Lord by praying out in the woods some place or even by watching Mass on television. God calls us to worship as part of His Church and to receive Him in the way He knows that we need.
Next, the priest greets us with either “The Lord be with you” or “Grace to you and peace from God our Father and the Lord Jesus Christ” or “The grace of our Lord Jesus Christ, and the love of God, and the communion of the Holy Spirit be with you all.” This is a heartfelt greeting that urges us to enter into the intimacy of the Mass. We remember that God is with us. In fact, in the Mass, Heaven touches earth in a very special way. We are called to open our hearts and our minds and our souls to God's grace and love. We are urged to enter into communion with God right now at the beginning of Mass so that we will be ready to receive Him in the Eucharist.
We respond to the priest's greeting with a heartfelt “And with your spirit.” At this point, we should say a little prayer for the priest as he acts in persona Christi and as Christ acts in and through him throughout the Mass.