The actual term “Holy Communion” does not appear in the Bible. This is a Roman Catholic or Anglican term for the taking of bread (or wafers) and wine. This is also called the Eucharist, the Sacrament of the Table, the Blessed Sacrament, and so on.
In the Bible it is called “the Lord’s supper”, or simply “to break bread”
1 Co.11:20 When you come together, it is not the Lord’s supper that you eat.
Acts 20:7 On the first day of the week, when we were gathered together to break bread, Paul talked with them, intending to depart on the next day, and he prolonged his speech until midnight.
Communion is an old Latin word for sharing, having things in common. In the King James Bible it is used in places where modern versions like the ESV generally have “sharing” or “fellowship”
Communion — among the believers
This sharing was part of life after adult baptism from the first days of the church:
Acts 2:42 And they devoted themselves to the apostles’ teaching and the fellowship, to the breaking of bread and the prayers.
It is also something that the apostles used to signal with a special handshake to show common purpose in the work:
Gal.2:9 and when James and Cephas and John, who seemed to be pillars, perceived the grace that was given to me, they gave the right hand of fellowship to Barnabas and me, that we should go to the Gentiles and they to the circumcised.
And Paul describes the donation of the church at Philippi as “fellowship” or “communion” with him in his work.
Phil.1:7 It is right for me to feel this way about you all, because I hold you in my heart, for you are all partakers with me of grace, both in my imprisonment and in the defense and confirmation of the gospel.
Or you all have fellowship with me in grace
No communion with darkness
It was also something that meant avoiding fellowship with darkness (2Co.6:14) but walking in the light:
1 John 1:7 But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus his Son cleanses us from all sin.
Meaning of the bread and wine
The taking of bread and wine was instituted by Jesus (Matt.26:26) and is explained as follows by Paul:
1Co.11:23 For I received from the Lord what I also delivered to you, that the Lord Jesus on the night when he was betrayed took bread, 24 and when he had given thanks, he broke it, and said, “This is my body which is for you. Do this in remembrance of me.” 25 In the same way also he took the cup, after supper, saying, “This cup is the new covenant in my blood. Do this, as often as you drink it, in remembrance of me.” 26 For as often as you eat this bread and drink the cup, you proclaim the Lord’s death until he comes.
The true meaning then, as seen here, is: (1) remembrance of Christ; (2) proclaiming his death (and of course resurrection); and (3) a sign till he returns.
Why is it so necessary to a Christian’s life?
Firstly because Jesus commanded it. Secondly because it is a very real sign, both to the individual believer, and collectively of belonging, together, to Christ. Thirdly because it provides an opportunity to meet together.
Luke 22:15 And he said to them, “I have earnestly desired to eat this Passover with you before I suffer. 16 For I tell you I will not eat it [again] until it is fulfilled in the kingdom of God.”
Heb 10:25 not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the Day drawing near.