The Synaxis of the Seventy Apostles was established by the Orthodox Church to indicate the equal honor of each of the Seventy. They were sent two by two by the Lord Jesus Christ to go before Him into the cities He would visit (Luke 10:1).
Besides the celebration of the Synaxis of the Holy Disciples, the Church celebrates the memory of each of them during the course of the year:
St James the Brother of the Lord (October 23); Mark the Evangelist (April 25); Luke the Evangelist (October 18); Cleopas (October 30), brother of St Joseph the Betrothed, and Simeon his son (April 27); Barnabas (June 11); Joses, or Joseph, named Barsabas or Justus (October 30); Thaddeus (August 21); Ananias (October 1); Protomartyr Stephen the Archdeacon (December 27); Philip the Deacon (October 11); Prochorus the Deacon (28 July); Nicanor the Deacon (July 28 and December 28); Timon the Deacon (July 28 and December 30); Parmenas the Deacon (July 28); Timothy (January 22); Titus (August 25); Philemon (November 22 and February 19); Onesimus (February 15); Epaphras and Archippus (November 22 and February 19); Silas, Silvanus, Crescens or Criscus (July 30); Crispus and Epaenetos (July 30); Andronicus (May 17 and July 30); Stachys, Amplias, Urban, Narcissus, Apelles (October 31); Aristobulus (October 31 and March 16); Herodion or Rodion (April 8 and November 10); Agabus, Rufus, Asyncritus, Phlegon (April 8); Hermas (November 5, November 30 and May 31); Patrobas (November 5); Hermes (April 8); Linus, Gaius, Philologus (November 5); Lucius (September 10); Jason (April 28); Sosipater (April 28 and November 10); Olympas or Olympanus (November 10 ); Tertius (October 30 and November 10); Erastos (November 30), Quartus (November 10); Euodius (September 7); Onesiphorus (September 7 and December 8); Clement (November 25); Sosthenes (December 8); Apollos (March 30 and December 8); Tychicus, Epaphroditus (December 8); Carpus (May 26); Quadratus (September 21); Mark (September 27), called John, Zeno (September 27); Aristarchus (April 15 and September 27); Pudens and Trophimus (April 15); Mark nephew of Barnabas, Artemas (October 30); Aquila (July 14); Fortunatus (June 15) and Achaicus (January 4).
With the Descent of the Holy Spirit the Seventy Apostles preached in various lands. Some accompanied the Twelve Apostles, like the holy Evangelists Mark and Luke, or St Paul's companion Timothy, or Prochorus,the disciple of the holy Evangelist John the Theologian, and others. Many of them were thrown into prison for Christ, and many received the crown of martyrdom.
There are two more Apostles of the Seventy: St Cephas, to whom the Lord appeared after the Resurrection (1 Cor. 15:5-6), and Simeon, called Niger (Acts 13:1). They also were glorified by apostolic preaching.
There are discrepancies and errors in some lists of the Seventy Apostles. In a list attributed to St Dorotheus of Tyre (June 5) some names are repeated (Rodion, or Herodion, Apollos, Tychicus, Aristarchus), while others are omitted (Timothy, Titus, Epaphras, Archippus, Aquila, Olympas). St Demetrius of Rostov consulted the Holy Scripture, the traditions passed down by the Fathers, and the accounts of trustworthy historians when he attempted to correct the mistakes and uncertainties in the list in compiling his collection of Lives of the Saints.
The Church in particular venerates and praises the Seventy Apostles because they taught us to honor the Trinity One in Essence and Undivided.
In the ninth century St Joseph the Hymnographer composed the Canon for the Synaxis of the Seventy Apostles of Christ.
Source
Read also: Synaxis of the Holy Seventy Apostles by St. Dimitri of Rostov
Apolytikion in the Third Tone
O Holy Apostles, intercede to our merciful God, that He may grant our souls forgiveness of sins.
Kontakion in the Second Tone
With hymns let us praise the chorus of the Seventy disciples of Christ, ye faithful; and in godliness, let us keep a feast, for we learned through them to worship the Trinity, Who is indivisibly one; for they are the lamps of our most godly Faith.
By St. Nikolai Velimirovich
Besides the Twelve Greater Apostles, the Lord chose Seventy Lesser Apostles and sent them to preach the Gospel, "After these things the Lord appointed other seventy also, and sent them two and two before his face into every city and place He intended to visit, He said to them, 'The harvest is abundant but the laborers are few; so ask the master of the harvest to send out laborers for his harvest. Go on your way: behold, I am sending you like lambs among wolves. Carry no money bag, no sack, no sandals; and greet no one along the way. Into whatever house you enter, first say, `Peace be to this household'" (Luke 10:1-5). But, as Judas, one of the Twelve, fell away from the Lord, so it was with some of the Seventy who abandoned the Lord not with the intention of betrayal but because of human weakness and faintheartedness. "As a result of this, many of His disciples returned to their former way of life and no longer accompanied Him" (John 6:66). As Judas' place was filled by another apostle, "So they [the Apostles] proposed two, Joseph called Barsabbas, who was also known as Justus, and Matthias. Then they prayed, 'You, Lord, Who know the hearts of all, show which one of these two You have chosen to take the place in this apostolic ministry from which Judas turned away to go to his own place'. Then they gave lots to them, and the lot fell upon Matthias, and he was counted with the eleven apostles" (Acts of the Apostles 1:23-26); so also were the places of these lesser apostles filled by others that were chosen. These Seventy Lesser Apostles labored at the same work as did the Twelve Great Apostles; they were co-workers with the Twelve in spreading and establishing the Church of God in the world. They endured many sufferings and malevolent acts from men and demons, but their strong faith and fervent love for the resurrected Lord made them victors over the world and inheritors of the Kingdom of Heaven.
HYMN OF PRAISE:
THE SEVENTY HOLY APOSTLES
THE SEVENTY HOLY APOSTLES
O knights of the Cross, sons of light,
You have not yet passed, O children of the future,
For you are not dead, as Christ is not,
But lives with life that never decays.
The Lord, You the Wreath-giver, beautifully crowned you
Because His Name, you loudly proclaimed
Before emperors and princes, before executioners terrible.
God, you served; but with torment, the world repaid You.
You walked after Christ, O bees of Christ!
The world you filled with honey; the vessels you filled!
Souls you alleviated; passions you calmed,
With Evangelical sweetness you sweetened life,
With the aroma of Christ, you censed the earth,
Salt, light and incense to the world, you were.
Seventy Companions, all with the same love,
As branches with the tree, with Christ, you were attached;
Seventy Stars, around the Sun - Christ,
And there, the angels are and the Virgin All-Pure,
There, unutterable delight, joy unseen,
Glorious victors of this transitory time.
Holy Apostles, glory and thanks be to you.
From your blood, justice blossomed.