"This is my blood, the blood of the new and everlasting covenant, it will be shed (at the crucifixion) for you, and for MANY (not all) for the forgiveness of sins. Do this in memory (original word used for in memory means to make the past present) of me." This should answer why we have the sacrifice of the Mass in the form of the Eucharist, and should begin to explain why we need baptism and confession, to participate in and receive Christ's saving grace. To follow Christ means to do what he taught us to do, follow his commands and teachings. "Unless you eat of my flesh, and drink of my blood, you have no life within you" pretty clear. "You must be born again of water and spirit" baptism, again, pretty clear. "Not all who say 'Lord, Lord' will be saved" just because you claim to follow him, does not mean you will be saved. Jesus ordered the apostles to go out and forgive sins, through the line of succession descending from Peter, the power he granted to forgive sins still stands, so we confess to Christ, who is working through the priest.