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Only practicing Catholics are permitted to receive communion (also called The Eucharist). Practicing Catholics are those who attend mass regularly and have been to confession in the last year. If you are not receiving The Eucharist, you are still encouraged to come forward with your arms crossed over your chest to receive a blessing if you would like!
We make the sign of the cross on our bodies by touching fingertips to forehead, chest, left shoulder, and right shoulder while saying "in the name of the Father, the Son, and the Holy Spirit" which acknowledges the trinitarian nature of God. The sign of the cross is a way of professing our belief in the Trinity and often done to prepare for prayer. All who believe in the Trinity are welcome to make the sign of the cross!
The water in the Baptismal font or little fonts on the wall is holy water. Dipping our fingers in the holy water and making the sign of the cross is to recall our Baptism as we enter the sanctuary. Again, all who wish to participate, may!
This refers to kneeling on the right knee and making the sign of the cross when entering / exiting the pew at the beginning and end of mass! It is a sign of respect, acknowledging God's physical presence in the church. It would be akin to curtsying before royalty or saluting a superior officer. All are welcome to genuflect, but are not required!
Please wait for the priest, servers, and newly weds to process out of the sanctuary before leaving your seat!
Nobody is judging you for not knowing the prayers or when to sit and stand. If you want to participate, watch the people around you for cues.