Pope St. John Paul II
“The Angelic Doctor also notes that the ‘effect of this sacrament is the unity of the mystical body [the Church], without which there can be no salvation. Therefore it is necessary to receive the Eucharist, at least by desire (in voto), in order to be saved’ (III, q. 73, a. 1, ad 2). These words echo everything Jesus himself said about the necessity of the Eucharist for the Christian life: ‘Amen, amen, I say to you, unless you eat the flesh of the Son of Man and drink his blood, you do not have life within you. Whoever eats my flesh and drinks my blood has eternal life, and I will raise him on the last day” (Jn 6:53-54).'”
Source: Pope St. John Paul II, General Audience, April 8, 1992