There is no need for a priesthood to offer sacrifices.
Jesus shed blood was enough and put an end to the system of sacrifices.
‘When Jesus had received the sour wine, he said, It is finished, and he bowed his head and gave up his spirit.’
John 19:30
http://www.biblegateway.com/passage/?search=John%2019:30&version=ESVUK
Jesus shed blood was enough and put an end to the system of sacrifices.
Catholic Priests do not "offer sacrifice." They re-present the original one of Christ.
Jesus said at the last supper to "Do this in memory of me."
To a Jew of that time those words have specific meaning. He said them during the Passover. Jews, to this day believe that in celebrating the Passover, they are participating in the original one. So when Jesus says to celebrate the Eucharist, He is saying we participate in that original one.
Please do not take my word for this go to the website "askmoses.com" and as them what they believe about the original and current Passover celebration. They do not view them as separate events.
"Do this in remembrance of me."
Sorry, we'll stick with Jesus' words! Have you never heard of a memorial before? (In memory of Christ)