Blessed Sacrament is a devotional term used in the Roman Catholic Church to refer to the eucharistic species (the Body and Blood of Christ). Consecrated hosts are kept in a tabernacle after Mass, so that the Blessed Sacrament can be brought to the sick and dying outside the time of Mass. This makes possible also the practice of eucharistic adoration. Because Christ himself is present in the sacrament of the altar, he is to be honored with the worship of adoration. "To visit the Blessed Sacrament is ... a proof of gratitude, an expression of love,... and a duty of adoration toward Christ our Lord."
Dogma includes divine revelation, i.e., the word of God (bible and tradition) and the word of God incarnate (Jesus), and truths connected to divine revelation. Dogma is immutable. Of the Eucharist, there are certain matters that are dogma and certain matters that are not, for example, transubstantiation is dogma but how transubstantiation happens is not dogma. An incomplete list of Eucharistic dogmas include:
The Catholic Church sees as the main basis for this belief the words of Jesus himself at his Last Supper: the Synoptic Gospels (Matthew 26-28; Mark 14:22-24; Luke 22:19-20) and Saint Paul's 1 Corinthians 11:23-25 recount that in that context Jesus said of what to all appearances were bread and wine: "This is my body … this is my blood." The Catholic understanding of these words, from the Patristic authors onward, has emphasized their roots in the covenantal history of the Old Testament.
The Gospel of John in Chapter 6, The Discourse on the Bread of Life, presents Jesus as saying: "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 remains in me and I in him" (John 6:53-56). According to John, Jesus did not tone down these sayings, even when many of his disciples abandoned him (John 6:66), shocked at the idea.
Saint Paul implied an identity between the apparent bread and wine of the Eucharist and the body and blood of Christ, when he wrote: "The cup of blessing that we bless, is it not a participation in the blood of Christ? The bread that we break, is it not a participation in the body of Christ? (1 Corinthians 10:16)." and elsewhere: "Therefore whoever eats the bread or drinks the cup of the Lord unworthily will have to answer for the body and blood of the Lord" (1 Corinthians 11:27).