How Does the Eucharist Link to Our Resurrection?
What does Jesus mean when he says we must eat and drink his body and blood to be raised on the last day?
What Our Lord means is that, in order to reach eternal life, each person must be linked to his death and resurrection through an active faith and love. We would say in traditional language that the fruits of his Passion must be applied to souls individually. The means Our Lord established in order to apply these fruits to individual souls are the sacraments, which are saving signs that link us to Christ's death, and the present grace he gives, and the reward of eternal life.
The greatest and most powerful of the sacraments is the Eucharist. This sacrament is thus the paradigm of salvation here below, and so Our Lord relates eternal salvation in the resurrection to our eating and drinking his body and blood by our faith and love for him in this holy sacrament of sacraments. Even if you are unable to receive him physically in the sacrament, you still eat and drink him spiritually by believing in his presence and by loving him. Thus, St. Thomas teaches that even little children who are as yet unable to receive the Eucharist nonetheless eat and drink of Christ by their faith and love for him in the holy sacrament.