You need to read the whole chapter of John 6 to understand what is meant by "They walked no more with Him." If you do you should clearly see that Jesus is talking about those that refuse to eat His Body and drink His Blood. That is what the chapter is mainly about. It is not symbolic.

Just recently while looking through the Fathers of the Church I noticed that there is an English copy of the Liturgy of James, the Liturgy of Mark and the Liturgy of the Blessed Apostles. The Liturgy is what is said in the Holy Mass. Just like the Latin Mass of today or the English or vernacular Mass of today the priest in these three old Liturgies above says something like this, speaking of the Holy Spirit "That coming, by His holy and good and glorious appearing, He may sanctify this bread, and make it the holy body of Your Christ."

The Sacrament of the Holy Eucharist has been offered daily for just about 2,000 years.

When the priest holds the Eucharist high, like this image below Catholics say (not aloud) the same thing that doubting Thomas said when he finally realized and believed,

                                    "My Lord and my God"

Also in John 6 when Jesus asks His apostles "Will you also go away?" Simon Peter answered him: "Lord, to whom shall we go? thou hast the words of eternal life."

I would like to invite everyone to attend a Catholic Mass at least one time in your life. I think you will realize that it is not the nasty thing that you have been told it is. Please be reverent if you do for you will be in the presence of Our Lord Jesus Christ. You won't rightfully be able to receive the Holy Eucharist without going to the Sacrament of Reconciliation before hand, but if you go up with your arms crossed on your chest like the young children do the priest will bless you.

God bless
Mike