The act of taking communion is done in remembrance of what Jesus did for us. This was based on his last supper and the elements in communion are a revelation of the true meaning of the Passover story. Transubstantiation, which is the idea that the communion wine transforms into Christ’s blood, is not a biblical concept. Blood drinking is not only forbidden in the Noahide (Gen 9:3-4) and Sinaitic covenants (Lev 7:26-27, 17:24, 19:26, Deut 12:16-25, 15:23), but also in the Messianic covenant (Acts 15:19-21). This is a sin for everyone, both Jew and Gentile, for all time from the beginning to the end.
In the Passover (Pesach) story, the Israelites put the blood of sacrificed lambs (or goats) on the door to protect them from death and they ate the lamb along with unleavened bread. In the new testament, Paul gave a little insight into the meaning of unleavened bread when he compares false teaching to leaven that spoils the whole lump (Galatians 5:9, 1 Corinthians 5:6). Leaven represents sin and Jesus is the only “bread” (human) that didn’t have sin nature, qualifying him to be our sacrifice. The wages of sin is death (Rom 6:23) and the blood of the Passover Lamb, covered the Israelites and protected them from the messenger of death (Ex 12:23). Likewise, the blood of Jesus makes us right with God and washes away sin, protecting us from damnation. Also, Passover was the last plague on Egypt ushering in the deliverance of the Israelites from slavery in Egypt. Likewise, Jesus’s sacrifice is the beginning of the new covenant, where he delivers the believers from slavery to sin.
It is not literal, it is a symbol in the context of Jewish Theology. The bread and leaven analogy of sin is an idiom that preexisted Jesus’s time on earth, and the blood of animals protecting the Israelites was a foreshadowing of the Messiah’s method of saving the world. This mechanism is sin in the Levitical sacrifice system. Jesus simply revealed what the old testament symbolism was pointing to, which is that he is the Passover lamb. According to Heb 10:1-18, Jesus fulfills the need for sacrificing so that under the new covenant there wouldn’t need to be animal sacrifices or a temple since Jesus was sacrificed, and believers’ bodies are the new temple (1 Cor 6:19-21) because the holy spirit (God’s presence) dwells in the bodies of God’s people, rather than a man-made Temple.
Lev 6:18 in regard to the grain offering and in Lev 6:27 in regard to the sin offering, both say “anyone or anything that touches the offering will become holy.” Jesus was the “anointed one” which means he was holy. When he touched a person who was ceremonially unclean like a leper (Matt 8:1-3) or a person with a discharge disorder (Matt 9:18-26) he made them clean. Normally people in these conditions would make others unclean and it was a sin for an unclean person to go around making other people unclean (Lev 5:2-3). However Jesus functioned as the sin and grain offering mentioned earlier, and anyone that “ate” the grain or sin offering was made holy or ceremonially clean. There is a principle that holiness was transferable according to Exodus 29:37; Exodus 30:29; Ezekiel 44:19; Ezekiel 46:20. “Eat my flesh” here is being used in reference to the fact he was a living sacrifice for us and he makes us holy. Jesus functions as the ultimate sin-offering since he died for our sins.
As for the grain offering, he called himself the bread of life (John 6:35), and bread is made of grain. The grain offerings had to be unleavened bread unless they were the first fruit offerings. Even then the first fruit offering made with leaven would be given to the priest because leaven couldn’t be burned on the altar (Lev 2:4-5, & 11-12). Only unleavened bread and clean (kosher) animals (like lambs) could go on that altar, at the temple/tabernacle in the Old Testament. Remember the word consume is used in reference to a fire. The fire on the altar consumes the grain and meat offerings. In the New Testament, the bodies of believers are the new temple since believers have the holy spirit (God’s presence) inside of them so, the “eating of his flesh and blood” functions as a reference to us receiving his unleavened bread (sinless flesh) and blood (as the lamb of God) on “our altar” because we (our bodies) are the new temples.
Lastly, the bible says multiple times not to drink blood in the Noahide (Noah), Sinaitic (Moses), and Messianic (Jesus) covenants. Gen 9:4, Leviticus chapter 17, Lev 19:26, Deut 12:16, and 25, Ezekiel 33:25, and Acts 15:20 and 28. So why would God have us do something so sinful? Lev 17 explains that the blood belongs on the altar poured out for our sins. The blood of a sacrifice is to be splashed on the altar, or on its horns, or poured on the ground in front of the bronze altar, which was at the entrance of the Temple/Tabernacle (Ex 29:12, Ex 30:10, Lev 4:7-34, Lev 8:15, Lev 9:9, Lev 16:18, Deut 12:16-27, Deut 15:23). Hebrews 9:11-12 tells us that Jesus took his blood to the altar in heaven because the Tabernacle of God in heaven is superior to the earthly one. Hebrews says the earth’s Tabernacle/Temple was only a replicate of God’s Tabernacle in heaven. Furthermore, Genesis 9 and Acts 15 show that all humans (including non-Jews), weren’t ever supposed to drink blood, not just those under the Mosaic Law. Jesus said in Matt 5:17-19, that he did not come to abolish the law (the Torah) and that not one jot or title would pass away even if heaven and earth passed away. Therefore, Jesus would never break the law by having us do something forbidden for everyone throughout the bible. So this cannot be what he meant in John 6:54 when he says, “But anyone who eats my flesh and drinks my blood has eternal life, and I will raise that person at the last day.” We are not drinking his blood since it has been poured out on the altar in heaven, the wine simply reminds of us the blood on the altar so that we can know that we are redeemed from the debt of our sins by his sacrifice.