It was above all on "the first day of the week," Sunday, the day of Jesus' resurrection, that the Christians met "to break bread." From that time on down to our own day the celebration of the Eucharist has been continued so that today we encounter it everywhere in the Church with the same fundamental structure. It remains the center of the Church's life. CCC 1343
As the feast of Unleavened Bread, called the Passover was drawing near, and the chief priests and the scribes were seeking a way to put Jesus to death, for they were afraid of the people.
But Judas, the one surnamed Iscariot, who was counted among the Twelve, went to the chief priests and temple guards to discuss a plan for handing him over to them.They were pleased and agreed to pay him money.
He accepted their offer and sought a favorable opportunity to hand him over to them in the absence of a crowd.
When the day of the feast of Unleavened Bread arrived, the day for sacrificing the Passover lamb,he sent out Peter and John, instructing them, “Go and make preparations for us to eat the Passover.”
The Last Supper
When the hour came, he took his place at table with the apostles. He said to them, “I have eagerly desired to eat this Passover with you before I suffer, for, I tell you, I shall not eat it [again] until there is fulfillment in the kingdom of God. Then he took a cup, gave thanks, and said, Take this and share it among yourselves;for I tell you [that] from this time on I shall not drink of the fruit of the vine until the kingdom of God comes.” Then he took the bread, said the blessing, broke it, and gave it to them, saying, “This is my body, which will be given for you; do this in memory of me.” And likewise the cup after they had eaten, saying, “This cup is the new covenant in my blood, which will be shed for you.Luke Chapter 22
The command of Jesus to repeat his actions and words "until he comes" does not only ask us to remember Jesus and what he did. It is directed at the liturgical celebration, by the apostles and their successors, of the memorial of Christ, of his life, of his death, of his Resurrection, and of his intercession in the presence of the. CCC 1341
Christianity is the ultimate inclusive set of beliefs - everybody is welcome. In the words of James Joyce
The Pope Francis' prayer video, released monthly, includes images of the Mass, especially the moment of the elevation of the Eucharist during transubstantiation — or the moment the bread becomes Christ’s body.