Excellent, belbab!
What does Jesus say is necessary for salvation? In John Chapter 6 (verse 31 and onward), it is believe in the Son of Man, eat his body, drink his blood and you will have eternal life--if you do not, you will have no life in you. The Watchtower says the "great crowd" must not partake, that they are unworthy of that gift and the eternal life it promises; they say that only the exclusive "annointed class" is worthy to partake, only they are worthy of eternal life.
Whether you take the literal meaning of Matthew 26:26-28, Mark 14:22-24 and Luke 22:19-20 or believe that the Lord was speaking symbolically, what matters is acceptance: do you accept His gift of "the bread from heaven", the "blood of the covenant", and the promise of eternal life that comes with them? That is what the Lord asks us to do. Or will you refuse the gifts the Lord has freely offered to you, thus refusing eternal life? The Watchtower teaches that you, as a member of "the great crowd", must say no to the Lord's offer. Scripturally, Witnesses who follow the WT mandate to not partake will not enjoy "eternal life on a paradise earth", because scripturally they will "have no life in them".