Wow! That is a hugh statement. I'm a Southern Baptist and we believe that Baptism has nothing to do with salvation. (How ironic :) Do Catholics really hold that keeping the commandments is necessary for salvation? Isn't that living under the old law? What is the Catholic view of the meaning of the new covenant?
Are you trying to say that by belief in Jesus, we "eat" and "drink" his body and blood?
Yes, that is fair enough. The level of appropriation grows through sanctification, and we remind ourselves of the importance of the sacrifice Jesus made for us by taking the Lord's Supper.
I agree with your assessment that verse 63 "flesh" was referring to weak human flesh. I was unclear in my point that Jesus was speaking of his Word(s) being actual life, as opposed to any action taken by human flesh.
Yes, one must keep the commandments of God, which are summed up in Mark 12:30-31: "You shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength . . .You shall love your neighbor as yourself. There is no other commandment greater than these."
Christ did not come to abolish the law, but to fulfill it (Matthew 5:17). Christians are not obligated to keep kosher, sacrifice animals, and such, but this does not mean that they can commit idolatry, adultery, theft, murder, etc without consequence. The Gospel and the rest of the New Testament are replete with admonitions that our conduct in this life (i.e., our keeping or breaking of the commandments) will effect our eternal destination.
As for the new covenant, we believe that it is being part of the body of Christ, sharing in His death and sharing in His resurrection. This is intimately connected to the Eucharist; at the Last Supper, Christ speaks of the "new covenant in my blood" (Luke 22:20)