Endurance, you clearly do not know scripture. While I do not agree with the Catholic interpretation of the wafers and wine becomming flesh and blood, Christ HIMSELF commanded us to observe this "Mithraic" ritual in rememberance of His sacrifice!
Communion is based on the Passover supper (which, as you know, was what the lasty supper was--a seder). There is a part of the seder in which a cup of wine is prayed over and everyone at the table drinks out of it. Bread is also broken and passed around. GOD ALMIGHTY HIMSELF commanded Israel to observe the passover, and Christ Himself commanded us to remember it's new meaning.
The root of Communion is NOT paganism, it is the Core and beginning of our beliefs--Judaism.
That said, keep in mind these things:
Traditions are just that. If you disagree with traditions with Biblical backing, then view them as unimportant as long as they are not CENTRAL componants of salvation (ie belief in the resurrection, etc.).
Since many Christians have let go of their Jewish roots, many do not celebrate Passover. Therefore, christians who participate in Communion are still upholding Christ's commandment.
Communion is an issue of comming before God and COMMUNING with Him, reflecting on the Precious gift of His son.
Endurance, HOW is this Mithraic?